What should I do with her breasts?

Here are some tips — that's TIPS — on breast-play along with this suggestion: ask your girlfriend how to handle, what is after all, a part of her body, as you so sensitively and respectfully pointed out in your question. As with her ears, lips, shoulders, stomach, hands, feet, yadda, yadda, yadda, you can try the following with breasts — and remember, your partner can help, too:

How fortunate your girlfriend is to have a companion with the caring and courage to ask such a question. Sex play is something we learn, not a skill-set imbedded in our genes that makes us natural-born pleasuring experts. Given the intense pressure that many of our cultures put on us to automatically love like Leonardo and move like Madonna every time we're intimate, it takes a real man, or woman, to ask for directions.