If you are a trans female I would just say to be yourself.
If you mean you are dressing up as a girl for Halloween, I don't know. It seems like that costume might be offensive to the trans community and possibly cross-dresser and woman. Think carefully if it would be.
Girls, we walk daintier, shave our legs and underarms, wear make up (watch Michelle Phan or Emma Pickles You Tube videos to get an idea how to do every day make up) and you will need a very close face shave. Women don't have facial hair. Be sure to blow your hair out and straighten it.