So many variables that can affect what you should do. One thing I do is pretty much treat those pairs all the same pre-flop. That means that I'll raise pre the same amount with any of those pairs (same amount for the bigger pairs, too, but that is a different question), or simply call if there has been a raise in front of me.
If there has been raising in front of me, and the players have been tight, or at least not hyper-agressive, I'll fold the low end of those pairs (22, 33, maybe 44). Otherwise call and hope to connect with a set.
If I'm short-stacked in a tournament, I'll likely shove with any pocket pair.