Group similer sounds like all your percusion in one group, synths in another and when mixing start with the drums and get them peaking at about -6. That way, after you haved mixed the tune and realise the drums are to quiet you only need to move 1 fader up a little, and you got head room to do it.
If you pan a sound quite hard to the left, make sure you got another sound that compliments the pattern and sound of it in the right.
After you made the sickest bassline you can imagine, DON'T stick a cheap reverb on it to 'fill out the mix' Put a imaging plugin on it and get it in mono. You can do the oppasite on the hi hats/percussion and give it a wide feel.
If you think the low end does seem abit 'mono' use a low lead line that follows your bassline. Roll off the bottom end with eq and use a chorus to give it a wider sound.
Can't get that Phat! kick & Phat! bass to sit side by side? Choose ONE to be the focus. If its the bass thats dominating the sub frequencys more do a 'High pass' eq/filter on the kick to give the bass space. Group the two together and stick a bit of compression over them. (dont' ask what settings
*DISCLAIMER -
These are some tricks I use. Im not saying there right and I don't care if anyone disagrees!

Oh yeah, I have copyright on them too so you cant use them anyway!