I am in an online MTT
I have 1375 chips having started with 1500, we are on level two blinds are 25-50, and I've not seen a single hand
there are three limpers into a pot and I am in the small blind with

I make up the blind and the big blind checks
the flop is

Hello!
I'm not doing a poll....but I can't ask for much better than that
I checked the flop and the initial limper bets 300 into the 250 pot, it's folded to me
I have no information on the bettor, he hasn't played a hand yet either
clearly I have to be afraid of a flush draw, there may be an overpair, or a set or a straight or straight draw or just top pair...lots of things to consider and,online, not much time
what is your move in response to the 300 bet? would you have led out on this flop, first to act (I am immeidately thinking check raise clearly)? if you raise, how much?
I'll tell you what I did and what happened later
thank you all