My first suggestion is that we have a "quick chat" menu where you can quick team chat or quick global chat something like "Enemy" or "Thanks" or "Cover Me!" or (I know a little much with the or's) something of the similar. TF2 has it and it's the only example I can think of right now.
My second suggestion is that the 3 current classes (or weapons I call them classes) all have separate skins like the classes in TF2 or BF3 do, this would help distinguish a little better between the three. I know you can have separate guns skins for each but sometimes they're hard to distinguish and plus someone might not even use gun skins either (I only mention this because that one person will bring it up).