HU --- how aggressive on a 8 or 9 out draw

[Zybomb]

NLHE: Lets assume you limp in with a hand such as 9h8h. There is a limp before you, and both blinds complete as well.

You flop either a 4 flush or an up and down straight draw to a non paired board. The SB leads out with a bet of 1/2 the pot and both players in front of you fold.

How often are you raising here, and how often are you calling?

If you choose to call, and the turn brings a blank, the SB then fires out another bet of 1/2 the new pot, how often are you calling and how often are you raising (or if you fold, how often are you folding)

Again if you choose to call and the river is blank, do you simply fold to a SB bet, or are you trying for a steal here? OR if the SB checks, how often are you attempting the steal with a large bet here?

I think situations like these come up[ frequently in both tournament and cash game play... Im hopin to get some good discussion on this topic.