One thing I want to add about Grenades. Max them as soon as you can, and do not increase the damage to any of your grenades.
I was a level 40 when I tried to max my grenades because I didn't learn how to use them till I was in my high 20's/30's.
So because I assigned skill points to make my nades stronger, and because I didn't level them till I was a high level, it took forever to finally max them. They made a huge amount of damage, and I got little rep from them.
This time around, I didn't assign any additional skill points to them, and I worked them early. They were much easier to max this time.
