Depends how deep the stacks are, and how loose the player is. Usually I 3-bet loose players a lot larger, sometimes up to 5 times their original raise. So if a loose player raises preflop to 8 cents, I would 3-bet to about 32-40 cents. To put that in perspective, if there are no callers or limpers a pot-sized raise would be to 27 cents. So I'm effectively over-betting.
Things do change based on stack size as well. Against short stacks, I'm 3-betting more hands that have immediate showdown value (AQ, KQs, AJs, 99). Against deeper stacks, I'm 3-betting hands that have more implied odds
(A3s, 67s, 33).
This also changes based on position. I'm more likely to 3-bet more marginal type hands that don't hit a lot of flops out of position (AJos), and in position I'm more likely to 3-bet with implied odds hands.