Rough guideline:

Bet strong draws (12+ outs to the nuts) almost always when checked to.
In LP you can bet weaker draws as well, but be careful on tables full of calling stations, as you may not have enough folding equity. Again your outs should be clean.
Monster draws (16+outs to the nuts) should almost always be played very aggressively.

Of course there are tons of exceptions and refinements, but this should be the basic plan I guess.

Don't go broke with the low full, non-nut flush or idiot end of a straight.

That's the best advice I can give you. Hold'em players stack off with bottom set all the time. Don't.