I usually prioritize skills over perks, and even then only grab the latter (remember, perks in general only take effect at 100%) when my crew is on their second slot so I can just drop and replace.
Edit: I was checking my tank stats, and I noticed how my B1's maximum experience gained stat seems to have changed from 1408 to 1716. The thing is, I don't remember having scored that kind of experience in a game, but apparently it happened within the last week or so. o_O You'd think I'd forget a game where I got that huge amount of experience easily.