I am still pretty nubish and not 100% sure that I am qualified to give advice, but I would have bet half the pot on the flop for sure. I would have done this for two reasons.

1. It checks to see where my hand stands
2. I can take the pot down on the flop.

I if get called then I procede with extreme caution, mosty likey check/fold. But at the very least I won't be forced to make a somewhat difficult call on the river. Thats not the place to be.