I like to gently nibble on the bottom lip. It usually drives them crazy. I love it when they do it to me too.
I do that to and my girl loves it but what she likes more is when i sick on her bottom lip. I alsi like to nibble her ear but im mot really sure if that is part of making out. Usually i do it before we make out. Also we have hicky fights. Sounds strange but we try to give each other a hicky without getting one. Its kinda fun. I usually win but she won once. Idk i guess its one of those things you just have to figure it out to understand. It may just be something special we do.