...a few more clues, like, whether you've asked her, have you experimented with anything else with positive results, that sort of thing. I haven't asked that one yet myself, come to think of it, so hopefully someone else can offer advice. Still might be good to offer a little more info.
Easy........try doing it privately first.....just between yourselves.
Take lots of pics of each other......see how you look together or individually........then maybe, just maybe you both might like to share your little sessions with the rest of the world.
Note: it does help if you are both hedonists. (*wink*)
we saw your request and thought about it for a while, maybe this could help you.
ask her to do a fotosession with you, just for the fun. then, as you go on, ask her to show a little more of her body, bit by bit and get her into masturbating. then you might give her some tips and get into action.
if you have a videocam in the corner of the room, taping what ever you do, you can extract the pics you want from the point you couldn't make them anymore being in action.
just make sure she knows it is taped, maybe even have it monitored on a tv.