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 // dA
Want to help create a US anime convention map?
COSPLAYS IN PROGRESS
Canterbury (Kuroshitsuji) - 30% - Kuro Gathering
Utatane Piko - default (Vocaloid) - 15% - Ohayocon
Boris (Alice in the Country of Hearts) - 3%
Jean (Shingeki no Kyojin) - 0%