What drum loops are you using? I use Beta Monkey drum loops and from my experience so far,i havn't done much to them.The Beta loops are already pre-mixed and the fills are already panned out so it's just a matter of getting a proper level for the song.
You can also try using some automated mixing if you need to raise or lower the level at some points or you can use another track to accent certain spots that need more attention.
I've only mixed one complete song with them so far & i'm learning as i go.So far i tried adding slight compression but it didn't really do anything but raise the volume.I can do that without adding compression so i decided against it.
I tried a slight bit of reverb but you gotta be careful with it.What may sound fine on one beat may be too much on another.Like going from a loop with a snare and kick to a loop with a ride or a fill with a crash.
Depending on the loops you're using maybe some parametric eq.I know i tried applying parametric eq but i can't remember if i kept that one or not.Like i said most loops are pre-mixed so anything you do is gonna affect the sound of everything that's contained in the loop.