http://forums.cosplay.com/showthread.php?t=99325 some things to remember about men.
Men have thicker eyebrows. if you pluck your eyebrows then you are going to need to pencil in some thicker eyebrows most like.
Men have a thicker jawline that a woman most of the time. Use a brown acceptable with your skin and a 'blue' (use LIGHTLY or you only look like you were bruised) use it to define your jawline and anywhere where you want the appearance of a five 0'clock shadow. Also perhaps find a middle color that can be used to help blend that dark to the light. I practice this step because it is really a pushing point.
Men usually have smaller lips. (only twice have I found a guy with TRULY girly lips XD one of those guys is my brother XD hehehe) if you have the nice feminin lips take some time and with a theater makeup that matches your skin completly (if not theater that just somehting that MATCHES) and look closely at the picture of who you are crossplaying (if it's anime just use a picture of a guy from a magazine m'kay?) try to match the shape of those purdy man lips. it took me a while to be able to do this properly if you don't get it right the first time keep trying. Also boys lips usually aren't so pink as a female's, get a more brown light layer of somehting over them.
unfortunelty for me I've never learned how to hide my VERY girly eyes
xd BUT that doesn't mean you can't experiment a little. most of this stuff I've learned by just experimenting. ^^ good luck!
also if you put up a picture of yourself ^^; it WOULD be easier to point out what you could do to look more masculine. BUT those tips should help none the less.
BTW work in a well lit area. XD the effects can be.......bad, if you work in a dimly lit area.
blaugh