I finally feel like I am getting the hang of this game after playing for something like a total of 4 days.
I know most of the maps (although I have not been playing the new ones that much) and still do a good amount of camping, but move around more from spot to spot. I have gotten my KDR up to 0.75+. It is going to be a while before I get it to 1.
For my first prestige, I unlocked the ACR and Assassin (I got a free token for being an elite member or something). I usually use Blind Eye (I do not like getting mowed down by helicopters), Assassin and Marksman.
For my next prestige, I will probably unlock Dead Silence or the Bouncing Betty. I really like the Bouncing Betty, it is great when I am camping as I can use it to protect behind me.
I have been using the ACR and P90 a lot lately. My KDR for the ACR is above 1.0 and I have been trying out the P90 as I have heard good things.