With the nut flush draw you usually have one or 2 overcard outs so I think it's okay to play this hand aggressively. Usually I'd lead out, and 3-bet if I am raised feebly and have 15 outs. I also like c-raising if opponent is known to take stabs at check-around pots.

Of course all plays are opponent-dependent, but whichever line one chooses the more aggression involved the better.