My wife and I mutually masturbate quite frequently. It really turns her on to watch me jack off. She loves the visual, the sound, and getting covered in cum. We've pretty much always done it mutually, we are both pretty liberal reagarding sex and enjoy it alot. There are times when we do it by ourselves which we are o.k. with. I would just start slow and gradually introduce it in your foreplay and then progress from there. It is a great turn on to watch your partner get off while your are just a bystander. Good luck and happy whacking!