Speed can never really hurt. More speed means more turns to place a TD and more often applying offense down. But you'll get most of your speed from secondary stats, so I'd recommend using Potency sets. She has solid health already so don't need to worry about that, she has ~40% potency I think to start off with, but more can't really hurt her. It'll help her apply Defense down and the TD (Also helps to give her offense primaries/sets as TDs also take part of attack power into account now as the potency check goes)
She doesn't really need anything specific to make her do her job as she doesn't exactly do a whole lot, but for the little that she does Speed and Potency are probably your best bets aside from finding a better scoundrel ;) (Sorry just had to add that in somewhere)