English isn't geared well towards gender neutral without sounding really awkward. Just refer to characters by their apparent gender until corrected.
Any player of a male character who gets offended at being called "he" or a player of a female character that gets offended at being called "she" really isn't worth wasting any sympathy on. Fortunately, such people, if they even exist, are quite rare; most people either flat-out don't care what pronoun you use, or will gently correct you if they don't want to be referred to by the gender of their character.
