Another really great way to setup your hotbars is to base them on what I'm calling Separation of Concerns:

- Main Bar is for GCDs I use in my main rotation, 1-6 and QERTFG (easy to reach)
- My Mouse buttons (M1-M6) are for commonly used DAMAGE oGCDs (easy to reach)
- CTRL+Mouse buttons is for CONTROLLING pets (SCH, SMN, MCH Turrets) or CONTROLLING damage (Tank Defensive CDs). For DPS, this is where my longer-cooldown offensive oGCDs live.
- ALT is for Alternative Strategies/Options. Silences/Stuns/Heavies/Sleeps live here, Elusive Jump/Second Wind/Bloodbath on DRG, etc. Used less often

Because I play multiple classes, I also make things consistent. 4 is my "buff" GCD (Heavy Thrust, Hot Shot, Straight Shot), 5 is my primary DOT (Phlebotomize, Lead Shot, Venomous Bite), M1 is my stun, etc. Obviously, I have a gaming mouse which helps IMMENSELY, but regardless you can see the basic idea. Keeping things blocked off in logical groupings really helps.