1] Scale down the size of your buffs. Debuffs can be big because you'll typically really want to know you have them, but buffs it rarely something you will want to look at in combat.
2] Your screen is fairly small, the border around your minimap is rather large. It's not a very good combination. Also I suggest a square map because it's more screenspace efficient.
3] Like said above, put something behind chat to make it easier to read. Will also actually make it look better. If you choose not to, atleast put the chat in between the top and bottom bars of your bottom panel.
4] Try download "move anything" and move your own unitframe to the left of your cast bar, and your target unitframe to the right of your castbar.
5] Move omen somewhere you don't have to look to the outer corner of your screen to see it. Also seeing move than the top 3 people on omen is probably not useful.
6] Hide your bags bar, move necrosis down