When I'm femme, I'm fully femme, but as a guy, I tend to get mistaken for a female A LOT, which mean I must be androgynous.
I agree, having long hair as a man helps. Wearing earrings all the time can add to that as well. As for clothing, try wearing denim, Hawaiian shirts, boots and other gender nuetural or borderline "colorful" clothing. I hate really bland clothes, so I try avoiding them at all costs. As of now, I can't dress fully femme in my day to day life, so little touches like these make presenting as a male a little more bearible.
