Our path to swinging started with us talking about our past sexual experiences, who they were with and which were particularly enjoyable. It was foreplay for us. My wife kept speaking of two guys she had dated as the best sex she ever had. I suggested that she contact them (separately), get together and see if the spark was still there.
Long story short - after getting together first just for dinner and introducing me by telephone to make it clear that I knew, the second "date" was for sex. So we started our swinging career by my wife fucking two of her exes separately, hotwifing I suppose. Eventually that led to us doing MFMs with them then regular swinging couples swaps with others.
Starting to swing with my wife getting back together with exes she liked was a good way to start for a number of reasons. It was comfortable for her knowing these guys. It was safe. She knew that the sex would be good (it was). I was fine with it because she had fucked them before, so there was no reason to be jealous. And they were exes for a reason: she liked them and was attracted to them, but realized they weren't guys she wanted to be in a forever relationship with. Maybe just a weekend.
So I highly recommend having your wife reconnect with an ex.