Short list of advice for casters:
-SPEAK UP
-Eliminate UMM...building a UMMMM Barracks and he's going to UHHHH attack with his UHHH marines
-Don't cough into the mic. Seriously. It makes my ears bleed. And if you do, say "excuse me".
-Don't tell me that you had to get a drink of water, I don't care. I can live with a short pause.
-Stop calling players "Sloppy". It's unprofessional. Just say that it's unorthodox or unique or something
-Don't bash the players. Again, it's unprofessional.
-"I don't know how I feel about this" I don't know how to comment on casters who say this.
-Is it that hard to note the names of the players at the beginning of your cast instead of saying "The -Terran Player" vs "The Protoss player"? If you were watching Hockey would you like it if the announcer said AND THE LEFT WINGER STREAKS IN
-Try to sound like you give a shit about the game
-But don't go OMG OMG OMG OOMG HUK'S PROBE IS HARASSING OMG HE'S GOING TO WIN 4 SURE NOW
-Call an even game. I realize it's difficult but try to eliminate bias.
-Check your sound settings before the game so that my ear's don't explode at the sound of your voice or the sound of a building warping in.
-Don't interrupt your co-caster. Don't talk over your co-caster. Determine who's doing the commentary and who's doing colour and play your freakin' role.
(This list somehow got longer than intended)