You don't you are too young at 12 to know your sexuality so leave it 2yrs or so then have a go -actually it is fine and you know at any age,just usaully over 11or12,not you DONT know like that idiot...
personally i look for some looks like for a second not to swallow i kinda look for boobs then if they don't have any i look for the same personalty and same scenes of humor and thas about it
depends on the individual guy.. all of them dont think alike!
The question is how much younger are you talking about? 15 14 13 12.....any younger its kinda taboo i am 17 and i like a girl who's 15...