From personal experience, my most fabbed pics are 1 of my bulge and an arse pic. The ratio of men to women who fabbed them is another conversation
I'd go for something that shows your personality though but that goes for all users man or woman
Depends what you mean by successful?
Make it to the hotpics successful? Penis - fabbed by shit loads of men
Garner interest from women successful? Something that shows thought and effort.