Without makeup and without a wig, it's pretty unlikely that you'll pass. 95% of people can't pull that off, and maybe 4% can pass as androgynous. I'd suggest you hit a few of the stickies and maybe the MtF Makeup thread I've seen around.
On that note, or maybe it's completely unrelated, I should post one of myself at some point.
facebook page // nh/mass cosplay events
Next event: ???
COSPLAYS IN PROGRESS
Actively constructing : Zell, Soren, Zexion
Back burner : Absol gijinka, Lie Ren
Coming next : Cloud