What's a reasonable weight to start out with for benching and also for squats?

I'm 5'9 and 150-160 with average build. I'm just wondering so that I don't look like a foo' in the gym trying all sorts of different weights on the smith machine. yea, yea...i know I'm not supposed to give a **** bout what other people think, but its a school gym and I know all those suckers...