One really big one I'm still TRYING to learn!!!! Stop putting compression on EVERYTHING!!!! Compression everywhere, tons of it..... must stop.... must stop!!!!! I'm working on it.

I don't just record myself. I got into taping b/c I love to listen.
 
Being mobile is really important to me. I love recording away from home or inviting new groups over to record.
 
Provides lots of good feedback from people who care (the band) and lots of opportunity to practice with different genres.
 
 

rodreb
One really big one I'm still TRYING to learn!!!! Stop putting compression on EVERYTHING!!!! Compression everywhere, tons of it..... must stop.... must stop!!!!! I'm working on it.

This is especially true for virtual instruments like synths. When you have complete control of the velocity/volume of each note, as well as all of the envelope/tone controls on the synth, there is often no need whatsoever for compression. Unless of course you're doing it for effect (like sidechain ducking or because an analog compressor sim adds grit etc). 

sharke
 
When you have complete control of the velocity/volume of each note, as well as all of the envelope/tone controls on the synth, there is often no need whatsoever for compression. 

This I completely agree with.
Guitar, Vocals, Bass usually get some compression in my mixes. I think it makes it sound better. Drums are more questionable - sometimes yes, sometimes no.

 
- Understanding that two "bigger than life" instrument sounds often (usually) sum up as unusable. There's only room for a limited amount of "bigness" of sound at a time.
- Har-Bal EQ. It made itself unnecessary to me in about three weeks  by convincing me of that the info my ears and Voxengo SPAN give me is reliable.

That when moving a fader up does not mean turning up the volume, but rather reducing the loss of the fader.

I have two tips to suggest.
 
ONE
Small, subtle changes goes a long way in a mix. Unless you are going for something radical and different, apply everything gently. This goes for compression, filtering (HPF/LPF), EQ,  delay, reverb, etc... A pinch of salt is a lot tastier than a cup of salt.
 
TWO
A good arrangement mixes itself with little effort. It's hard to make something stand out if everything else is going "full tilt" around it. Listen to some of your favorite recording and you will find that the arrangement of the parts created more openings and space than radical EQ or compression did. 
 
Just my 2 cents...

This might sound silly, but simple mic placement has been getting lots of play with me lately. The amount of mileage I've been getting out of putting on headphones, monitoring input, and moving a mic in front of a guitar cab is amazing. I recently tracked clean e-git for a raggae act and had to do no eq at all...just an 80ish low cut and that was it. If you're just slapping a 57 on-axis an inch out from the cab you're really missing out. And it's not big moves...small moves make big changes, especially with axis. Want to cut the HF harshness from a 57? Rotate the axis a bit. Also, rotate your vocal mic a few degrees off axis to save yourself a bunch of de-essing.
 
Save processor cycles...use less EQ and just move the mic.
 
Dean

Mixing with monitors instead of headphones when getting into the late stages of mixing.

ce
cut instead of boost

yes mister!