String bikini is definitely best. (Strapless just squeezes too much and it just ends up looking weird. I feel the same way about wedding dresses.)
Some sort of pattern also works great on it, but not like a stripe or dotted. More of like a print, like flowers or tie die would work. Shiny also works great. It accentuates features, making it easier to see curves and possibly some other stuff. Wink, wink.
i think that would depend on the girl. girls with small busts look best in bandeau usually. girls with big busts usually look better with more support so halter bikini tops with a thicker band on the bottom. patterns distract from flaws usually but sometimes make things look bigger or smaller so it really depends on the girl.