Off the top of my head...
Make sure that the cards you need to complete your hand are all live. On third street with a pair, I'll toss it if any of the cards I hold are showing on the board. Definately don't play if your pair is partially dead.
For a 3-flush, if more than 2 of the suit (or the A) are in other hands, don't try drawing to it, dump it (the exception here being when you get down to the final table and are shorthanded).
Don't draw to straights, unless at least 2 (and preferably all 3) of your starting cards are suited.
I generally make folding decisions on 3rd and 5th street. If I play the hand past 3rd, I'll always see it to 5th, and once I call a bet on 5th, I'm in to the end unless they have an open pair that beats my hand.