speaking from a males point of view, the neck. gentle biting on the neck. kissing too. not forgeting the ears sucking, knibbling etc.leave the penis out. i find that if my gf started to mastabate me then it just starts to relieve any tension you have. tease a lot, hold 'em down! seems to be fun. stop them from kissing you and pretend like your gonna kiss them, but dont. then after a bit, kiss them gently on the lips then work your way to the neck.
i hope this advice is helpful, x