1) Bind everything you can. I click to use quest items and open trade skills. . . but that's about it.
2) Bind the skills you use more frequently close to your natural hand position. I use ASWD to move (some people use EDSF or RDFG) so I bind instant casts to buttons like R and F. Mouse buttons also work out really well for these kinds of skills.
3) Bind skills you use out of combat far from your natural hand position. I use (8,9,0 and F5-F12).
4) If you still have skills left over use Shift, Ctrl, and Alt modifiers (these work for mouse buttons too).
5) THIS STEP IS CRUCIAL. . . get a bar mod that allows you to hide all of your skills. If you hide them all you're forced to remember the keybinds and use them. Not going to lie, this will suck for awhile b/c it's like having to relearn how to play. . . but it's worth it in the long run.