It's still Friday where I live, so:
 
Soft Synth patches are not going to work for your mix until you edit/fix them. (This goes for hardware ones too). This is especially true if you are mixing together more than one patch into a piece.
 
Another way to put it: don't be mesmerized into a false sense of sonic nirvana by the "big" sound of a lush synth patch and then just drop it into your track, set the level and consider it "placed". Lush synth sound + another lush synth sound + another (etc) == MUSH synth sound.
 
Remember that you are working at cross-purposes from the sound designer who saved the original preset(s). When a sound designer finishes a preset, he or she wants it to shine on its own (and entice you into buying the library, all good). When you put said preset into your latest dub mix, it is not longer a solo entity and has to be tamed to fit with the other presets. It shouldn't sound good by itself anymore, once you have it properly set into the mix.
 
Aspects of synth presets that need tweaking--or possibly gutting.
 
First and foremost, turn OFF the preset's reverb effect. Lots of synth presets (the majority?) come with reverb turned on, to make them sparkle. Your total piece is better served keeping the sparkle out of the picture, until later in the chain when you add your own judicious sprinkling of a reverb effect (or two) on a buss and direct sends from your synth tracks out to that sprinkler system (sort of your sparkle sprinkler, if you will). Imagine a mix with, say, four synths (or more), each with its own reverb going, all mushed together, causing a lack of clarity and focus. (Um, unless you don't want clarity and focus in your mix, in which case, skip this step.)
 
Check any LFO-based effects and adjust them to fit your creation. The sound designer added, say, a fading ping to a sound at some arbitrary low frequency. Sounds great by itself, but, since the odds of said sound designer reading your mind are pretty slim (at least in this pre-singularity age in which we are trapped), the LFO frequency does not match what would be best for your finished sound. Maybe (probably?) the LFO should be synced to your tempo: quarter note? eighth note? What are the other synths' LFOs synced to? Experimenting with different sync settings on each patch maybe called for here.
 
Gotta do some equalizing, but you know that. Lot's of presets, as I've said, try to sound B-I-G! Your piece should sound big on the master buss, not each component of it. Chip back those big sounds to make them fit.
 
Watch resonance, and other settings that might build up in one frequency range. You might be liking a handful of presets because, without your even realizing it (oh, the blindness of inspiration!) their resonant filters strike your fancy (and your ear) in a good way. Which is good, in a way. But if they're all striking you in the same sonic neighborhood, you're going to get ear fatigue. (Or, much worse, you audience is.) Rough up those complacent resonances, I say, or at least pan them far away from each other.
 
I'll bet, when you start poking around, you'll find other settings in your favorite synth patches to beat into submission. (Creativity makes YOU the boss.) The bottom line take away executive summary: Synth patches rarely, if ever, sound their best in a mix with other instruments/patches without some sculpting. (C'mon, flipping on the ol' HPF cut at 40hz is hardly sculpting and I think you know that.) Make it a rule to think of synth patches as "raw" synth patch pre-sets. They're not the finished sound that you want throw, un-cooked, into your mix. They are the beginning inspirations that you will want to peel, chop up and blend in, using your own special seasonings.
 
Okay, now I'm getting peckish.
 

GREAT advice, well-stated, and I agree completely. Thank you very much!

Anderton
GREAT advice, well-stated, and I agree completely. Thank you very much!

+1

mix remix then remix
is my tip
I know its weak but whatever

It's not quite Friday, but I'll be busy tomorrow and might not get to it.
 
A lot of us record in spare bedrooms.  Mine is "treated" somewhat with some high frequency absorbers and some mid-bass traps and you can tell when you walk in the room that the sound is fairly dead.  However, there are still some killers to recording anything with a mic in that room:
 
Ceiling fan - turn it off.  it might get hot, especially in Texas and other hot temperature zones, but if you leave it on(or any fan) then you will "chop" the sound with the fan and it will record that way.  in the recording it could show up as a chopping sound or as a phasey noise in the recording that you can't identify otherwise.
 
door - close it.  there are always noises "down the hallway" you might capture during that excellent acoustic guitar riff you've been practicing for weeks and finally got it right during recording...just to find out that you can hear the dog in the other end of the house moaning while he scratches himself.  or the dishwasher kicking on, or the TV in the living room being turned up by your teenager watching MTV...
 
avoid parallel or "normal" lines with planes in your room.  (HUH?) yeah, I'm speaking geometry.  you should probably know what a parallel line is, don't set up your mic's so that the source (the thing you're recording) is directly facing a wall (normal to it, or so that it makes a 90 degree angle with the wall you're facing) nor set it up so that the source is exactly parallel with one or more walls.  use offset angles to all flat surfaces you can.
 
Bit talked about using a pop filter for keeping your distance between the mic and the mouth of the singer.  yes, that's good, but also know that too much of a distance between the mic and the singer is a bad thing.  that will introduce your room sound and you can't really effectively filter that out.  if you know what you're doing and you WANT the room sound, that's a different subject.  but if you're recording through a mic and will be adding reverb later, don't stray too far from the mic unless you're popping out some SPL's and need to "work the mic."  quiet passages should be sung very close to the mic (I like to use 1 to 2" on either side of the pop filter).
 
it's a recording, not a party.  remember the more people you have in your little bedroom studio during recording, the more likely one or more of them will make a noise that gets recorded.  sometimes the noise is embarrassing.  just sayin'
 
if your bedroom studio has a window to the outside, cover it up with curtains or some material during recording.  this will help keep the road sounds in front of your house out while keeping your high frequencies inside from bouncing off of the glass.
 
turn the A/C or heater off if you can during recording.  There's a guy on these forums who used to post songs in the songs forum all the time and i'd always say, "Kevin, this is great, but what was that sound at 2 minutes?"  Kevin:  "Oh, dawg you've got good ears...that's where the air conditioner kicked on, it was getting stuffy in here!"
 
Don't forget to save often!  I know this is such an obvious one, but I've also had a situation where I was excited to be recording an ensemble of 8, go them all set up and they're using earbuds/headphones to listen to a backing track while singing into some "choir mics".  when the session was over, one of them was helping me tear things down and turned off the power strip which was running the headphone amp for the ensemble.  unfortunately, it was also running the computer and I had forgotten to save the entire time!  luckily you can almost always recover the raw wave files since they're saved as they're being recorded.  but it sure did scare the bejeebers out of me!

OK, if Beagle's gonna cheat, I will too. 
 
I've not done a lot of live remote recording, and always struggled with not being able to hear what's coming through the microphones when it's a loud band. I could only watch the meters and hope for the best. Normal headphones just can't isolate well enough when you're close to the stage. Or worse, off to one side of the stage.
 
Then I remembered that I had a pair of ear protectors hanging up in the garage and did an experiment. I used my Shure in-ear monitors and clamped those ear protectors over them. Instant silence. Some lows still got through, but we were taking the bass direct so it didn't matter. Guitars, vocals and drum overheads could be heard clearly and at a reasonable volume where clipping, tone and bleed could be easily evaluated.
 
Ear protectors are cheap and available at any hardware store. They also provide an additional benefit, which is to, well, protect your ears. 

Make sure your levels are correct and not in the red.

"Broken" ear buds make inexpensive vocal tracking headphones.
 
If you have a set of ear buds that you're ready to throw away because only one bud works, don't throw them away.  Instead cut off the broken bud then use the remaining bud as a headphone while recording vocal tracks.  Mix your vocal guide track to mono, pan the guide mix to the working ear bud channel, set your volume level, cover your ear and record.

Happy Friday the 13th. In honor there which of, I call this tip "I'm feeling lucky" (or "this patch sounds awful, I think I'll use it").
 
This is a tip/creativity idea for your "stuck" projects. You know, the ones that are getting mixed, but don't seem to be getting any closer to generating a spark, much less setting things on fire. All the tracks kind of fit, but....it's just--I don't know--lackluster overall. (Not that this has ever been my experience--nor yours! I speak hypothetically.)
 
What to do? Here's an idea for potentially pumping some pizzazz (whoops, better use a pop filter!) into a project that works for me when a project gets stuck (um, hypothetically). Or if I'm just feeling goose-bumpy with creativity and I want to try something new.
 
This is based on the notion of, when you are mixing, NOT soloing any particular track to listen to it. Always mix (goes the dictum, to which I try to adhere) of not making any audio judgments out of context. As mixing progresses and each track is aurally "sculpted" to fit with the other tracks (the context), each track--listened to by itself--might sound yucky (to use the technical term). But that's okay, because it's out of context and so it won't be heard that way in the real world--so don't listen to it that way. Make all mixing/sculpting decisions and adjustments ONLY when listening to the piece as a whole--all tracks playing (at a modest listening level, of course--Messrs. Fletcher and Munson are watching you!)
 
So here's the tip to try (really, try it!): Purposely put a yucky sounding track into your mix and listen to what happens (in context). As an example, let's say you're using a Dimension Pro bass patch. Lots of them to choose from (many dozens), but, maybe like me, you only ever use a handful of your tried and true favorite bass patches with which you are comfortable. What I am suggesting is that you swap out one of your fav patches (currently in the mix that is going nowhere) with a bass patch that you know in your heart of hearts that you would never, ever use, or--even better--one that you have never, ever even listened to! (I mean, "FG Crazy Donald"? Really?) That's the patch to try, BUT don't listen to it by itself--don't even press a midi key. Slap it into the track, guess at the level setting and start the track rolling. Go ahead and hack away at the EQ and effects, etc. but always in context. You'll probably hate it, but...you might love it!
 
The bass example is a simple example. Try swapping a fat patch with a thin patch or an "8va" sound with an "8vb" sound. My example caters well to synth tracks, but the same idea will work with guitar track amp models, with keyboard tracks (try a dirty Wurlitzer instead of a Steinway, why not?), heck, with entire drum kits. Pick a kit you've not yet touched (because this is a ballad and why would I use a metal kit?), plug it into your soon-to-be masterpiece and give it a chance (just as if you had a "real" drummer come in and audition with your band--"let's take it from the top and see what you've got.")
 
This technique does not fall into a "traditional" record/mix/master model. That's okay, too. It's a non-linear (NLE)world now, so embrace it. So you're mixing, that no longer means the instrumentation is set in stone. (It could mean that, but you're then missing out on a lot of what a 21st century DAW has to offer.) And guess what? Sonar just added "take recall", so you can mess up--er, I mean, "constructively deconstruct" multiple tracks with multiple alternative patches/effects/kits etc. Be fearless! If you go too far afield with new, off the wall ideas that you just know will sound terrible, a) good for you; b) you can always breadcrumb your way back to civilization (eg, the bland mix that you're trying to spice up, remember?); c) hey, in context it doesn't sound all that bad! Why not print a copy--with the "new" track sounds that you swore you'd never use, why did Cakewalk (or whomever the vendor is) ever include those dorky patches anyway?--to a CD and try it in your car on the way to work tomorrow? Why not print a couple of alternatives and try them all out to listen to on the way to work? Tomorrow's car trip might start of a new friendship with your (formerly) lifeless project.
 
PS. I didn't use the phrase "think outside the box" even once during this diatribe. Pretty proud of myself.

Nice tips thanks.