As a caster DPS in a raid setting, there is a small handful of things that are important.

1. Your castbar.  This should be front and center, not up and out of the way at the top of the screen.  Maximizing your DPS in raid is going to be about seamless casting, CD's and proper cycles.
2. As mentioned above CD's are generally crucial to your DPS.  You want to pop all that you can as often as you appropriately can.  Your CD timers (visible anyway) are pushed way off to the right with little growth room.  I would suggest making these more central and more visible.  Then again, maybe your main ones are, and they just aren't showing in this shot.
3. Your target should not be a tiny afterthought as it appears to be in this screenshot.  Knowing the target's health let's you know when to dump mana, get more mana, push threat harder, etc, etc.  This needs to be more central and much larger.
4. Threat is probably the other killer element.  Yours is probably sufficiently sized/placed.

Less important to DPS, but potentially important to staying alive on some fights, is having a close look at your own health and having a generally clean ui area.  Fubar should help you un-clutter you mini-map.  I usually suggest that people drop the cutesy fonts and such nonsense in raid.  Clarity and readability are more important, though maybe not enough to get in a fight over.