Drawing Hands
 

I'm playing regularly in a fairly loose, $100 buy-in no-limit Hold'em game. It's all going about as you'd expect, but I seem to get in trouble with drawing hands. Anyone have profitable advice on:
1) Whether to bet open-ended straight and flush draws in early position. If so, how much?
2) How do you account for later action when calculating pot odds? In other words, it's easy to determine whether you have the right price to call on the flop, but if I don't make my hand on the turn, I'm often faced with a much larger bet, that doesn't give me the right odds to call.

By throwing my hand away, I've made my call on the flop incorrect, since I'd figured my odds on seeing two cards.

If anyone could point me in a good direction, it'd be much appreciated.

Best,
Langworthy