Unless you have huge delts, bi's, or tri's, you're gonna have to split the 3cc up. 2cc is the most I'd personally want to shoot in my delts, and I've got a pretty large frame...
I personally find 1cc bicep injects pretty much painless if the gear is good and you don't go and pump out heavy curls afterwards (treat your arm the same as after a blood test; don't carry anything too heavy for at least a couple hours... shit like that).
Don't overlook trapezius injects if you're looking for a quality site. A little strange, but not all that painful (IMO). Especially if you're using 23-25g or smaller.
Tri's aren't so bad, but I'd hit each side with 0.5cc to start.
Quads are great for 2-3cc injects if you're sick of glute shots; make sure your gear is painless before you hit the Q's (just my experience).
For the hardest of the hardcore (or, the most comfortable with needles and their injection technique), try the outer portion of the forearm(s). No more than 0.5cc to start, but it's great during ED 50mg tren cycles when you've gotta hit a ton of sites with something like a 25g 5/8" or 1".
Hope this helps!
-M