but
 
 
if you DO have an arrangement, 
that is TOO dense,
you must learn how to do complementary Eq.

Sometimes if I have these clashes, I like to into a part (guitar riff, perhaps) in isolation. At the beginning of a song, bring it in, by itself, or nearly so. Keep it prominent for 8 or so bars - the listener will get used to it being there, nice and up front.
 
Then when you add the next element, you can drop the guitar 1 db or so, the listener will know it's there because they are used to its being there. You can raise volume on the next element.
 
When you bring in #3, lower number two. etc. etc.
 
This in addition to panning/eq can help unmash the parts. And as they say, for most people it's all about the vocal anyway.
 
cheers,
-Tom

I am not against complimentary EQ at all. I think it is an important aspect of mixing. Because as Bats says some mixes are dense.
 
But arrangement changing is really a strong and powerful way to go about it instead. Many bands overplay (that is why they sound amateur) and so do we as we are tracking and stuff.  What all the great songs have in common is the use of minimal parts and statements that still convey the message really well.  Somehow there is air in between or the black backdrop becomes visible.
 
I found this when I took over from a drummer in a Roy Orbsion tribute show band. They gave me some CD's to listen to and it was the band playing some of their last gigs before I took over. What happened though was everyone in the band were taking far too many liberties and everyone was overplaying to blazes. (tempos also went right out the window and were way too fast, horrible) When I went right back to the original tracks it was very obvious.
 
I made noise at the rehearsals and suggested we get right back to the original parts and I mean exactly as they were. (and tempos) After some work the music sounded 100 times better! You see Orbison had great producers all along the way who agonised the parts and worked all that out so my theory was simply lets listen to it again and get it right back to that point. We did not allow it to deviate ever after that and it sounded fantastic for over 5 years.
 
Arrangements!
 
(Listen to Kraftwerk. I know not everyone's cup of tea style wise but in terms of only the minimum being there it is a real eye opener!! He was a master at this.  It teaches you how to keep arrangemets sparse and powerful and fat too.  No complimentary EQ going on there because almost nothing overlaps)
 
emeraldsoul also makes a very good point. Once parts are established you can turn them down and more than 1 dB as well. Even a 3 dB change when something else comes in still sounds like it is still there and in the picture.
 

Another real world example is my main band LORD. If you ever listen to us (link in the signature below), the first thing you'll hear is a LOT of layers, like literally hundreds of vocal layers, up to 25 guitar tracks, synths, loops, sometimes 2 different bass tracks, and usually very fast and busy parts, especially drumming wise where the kicks can be very full on.
 
Mixing that is a HUGE challenge, let me tell you! But where possible, yes - the arrangement favours the most prominent element. Is the guitar riff the key? If so, does it REALLY need the kick drums to follow every note? Can the bass do something in a different octave? Hang on a note? Stop entirely?
 
And yes, sometimes it's absolutely necessary to be that busy. You'll have a very proggy tech riff where everything is playing - the guitars and bass are mirrored over the top of a double kick section, with orchestration and vocal adlibs - and that's crucial to getting the intent of that part across. It's in those places that you really need to put your objective engineer hat on and decide what needs to take focus most of all, and put any ego aside (and as the lead vocalist and guitarist that also does the keyboards, that's a hard ask for me! HAHA!)
 
But yeah, some great suggestions in this thread and things I've pulled out pretty often when I manage to write myself into a tangled mess! 
 
One last thing to consider is your ears lie.
 
I think I mentioned in anther thread somewhere that I made a complete disaster area of our first proper album back in the 90s. I listened to each track in isolation, and got everything sounding absolutely MASSIVE for each track on its own, and then naively sat there like a drooling idiot wondering why it all sounded like a muddy mess once everything was all combined in the mix, and then every change I made after that was just more tangling. I'd turn up the guitars and you'd lose the kicks. I'd turn up the kicks and then the bass was getting lost. I'd turn up the bass and then the guitars sounded wimpy. So I'd turn up the guitars and... repeat from step one, watching the other band members getting more and more angry I'm wasting our recording budget.
 
That's just half of it. The other half is your ears really get attuned to what you're listening to, and it's a very distorted view of reality. This same album is a good example. We finally got something we all could live with (barely) and took it to get mastered. We put it next to the reference tracks and everything else we listened to sounded wrong and kind of thin and midrangey. In actual fact, everything else was fine (of course it was, since it was all done by pros with a huge budget), and it was our stuff with no mids and a sloppy low end. But none of us could hear it objectively anymore.
 
You really need constant reality checks with commercial mixes as you go to keep your brain in check. Changing anything, even for the better, will sound wrong if you're caught up in your own mix. So cutting the lows on the guitars to carve space will make them sound bad if you're used to that mud being there, but if you compared it to a commercial mix, you'd probably find that's exactly what they did to get that to sound so good.
 
Anyway, just a couple more things to consider. 

Jeff Evans
I found this when I took over from a drummer in a Roy Orbsion tribute show band. They gave me some CD's to listen to and it was the band playing some of their last gigs before I took over. What happened though was everyone in the band were taking far too many liberties and everyone was overplaying to blazes. (tempos also went right out the window and were way too fast, horrible) When I went right back to the original tracks it was very obvious.
 
I made noise at the rehearsals and suggested we get right back to the original parts and I mean exactly as they were. (and tempos) After some work the music sounded 100 times better! You see Orbison had great producers all along the way who agonised the parts and worked all that out so my theory was simply lets listen to it again and get it right back to that point. We did not allow it to deviate ever after that and it sounded fantastic for over 5 years.
 
Arrangements!

 
I agree with you Jeff.  I started playing Live again about 6 months ago with our Worship Band.  I noticed immediately that when everyone is over playing their parts, it became a mess.  Not only with overlapping of instruments, but timing was all over the place.  The band Leader has made the comment that when I play Bass the overall timing of the band seems to be in sync, more than when some of the other guys play.  I told him that my focus is to stay in the pocket, support the drums and rhythm section and not to try to do runs up and down the neck.  They have taken notice and seem to sound better as a result.  

I remember reading an interview with Ken Scott. He said the most universally ugly frequency is 200hz.  So he basically does a cut @ 200 on almost everything. I didn't know if it was some sort of joke so I tried it and damn if it doesn't make a great place to start.

Rbh
I remember reading an interview with Ken Scott. He said the most universally ugly frequency is 200hz.  So he basically does a cut @ 200 on almost everything. I didn't know if it was some sort of joke so I tried it and damn if it doesn't make a great place to start.

This is a very good point. I tend to apply the 200-300Hz scoop over the whole mix rather than trying to do it on every channel or track. And yes it often makes a mix instantly more clear and nicer. There does seem to be a build up around that area that many forget about.
 
On Harrison Mixbus would you believe on the master buss is a real nice EQ and the control in the middle is centered right around this area. It might be call Mids or similar but it is not.  It is around 300 Hz instead.  All you have to do is move this control to the left and all the mud is gone! Excellent.
 
If you do this manually though you need to be careful of the shape of the bell around this area and how deep you make this notch. You can also overdo it too and find you are sounding too thin as well.
 
 

yes, i'd agree with jeff on using the scoop....
on a parametric, i'd start with a real High Q, and a real deep BOOST to find the exact center point of the mud...
 
then, go the opposite way, but go to a shallow Q (like 4) and only do about 1-2db of cut.....
to taste.....
 
i tend to eq individual tracks, to get rid of mud and maximize the low end,
sometimes it's confusing solo'ing a track to do that,
but after some time, you kinda KNOW you are hearing mud on tracks you know don't need that freeq......

Regarding weaving parts in the arrangement, this is why I love working with MIDI in the piano roll so much. You can have multiple parts showing on the same roll and instantly see how they're clashing with each other (both in timing and register) and rewrite them so that they mesh together. Sometimes you can write very intricate weaving parts like this which sound very dense while never stepping on each other.

And register, there's another area to look at. Very easy to invert chords note by note into a higher or lower register so that they don't clash with other parts. You just take the bottom note of the chord and drag it up and octave (or the top note down an octave) - rinse and repeat until the chord is in a register which works better. And sometimes these new inversions add a totally different flavor to the sound.