Like many my wife is kind of shy when it comes to her body but we are at the point where she likes flashing now. The first few times we tried it she was only naked around my friend, we had talked about switching partners and stuff but she was not comfortable going too fast.
She quickly got used to being naked in front of him and she did it probably 6-8 times before we brought his wife into the picture. We stripped each other's wife and started feeling them up pretty well when my wife decided she couldn't quite do it yet. She stopped the action and asked that we go back to our respective partners which we did and respected.
A few weeks later he was there and she was naked and we let him go all the way. Once she had sex with him she felt she could take me having sex with his wife. I went to their place a few days later and I had sex with her. Finally we got together and we were successful with the switch. We did this a number of times after with no problems.
It just takes time and understanding and a lot of communication between us. That was key and now we are looking online for new people to have some fun with. In the meantime we are having fun with still flashing her and this site is perfect.