The opponents have opened the bidding, and there you are, wondering whether or not to compete. Here's what you need to join the party.
7 to 17 pts. If you're going to overcall at the two-level, you need 10 plus.
A Darn Good Five-card suit. The worse your point count, the better your suit should be.
Why should you look for a reason to overcall? The hand might be yours, either partscore or game. It also gives your partner a lead, and harasses the opponents. Be careful though that you don't overcall just hoping to push the opponents too high. Good players won't let you do that and YOU'LL end up in trouble!
Let's try some.