preflop - I don't usually raise A9s, maybe I should?

flop - ok

turn - I would do the same as FishMagician here: put more money into the pot. Even though a flush draw is unlikely, I hate being in a position where I might either lose a big pot or win a smaller pot on the river. Bet now while you are ahead, not later when you might be beat. You have to bet some time, and he might even be more willing to call you on the turn than on the river if he has a chance to draw.