Been through this. Just make sure you devote more attention to your spouse than other participants.

We are new swingers too it's hard trying to find another couple

I think it would be better to start with one, so a threesome and I think it should be a guy with a nice cock as at his age and after all of those years together I bet and know that he would love to see you suck and fuck a nice big cock while you look deep into his eyes wanting more of his big cock and your husbands cock, and your husband will be in a dream and then after a while have another threesome but with a sexy younger woman and watch your husband fucking her younger pussy hard and after that ye should know and feel if ye want to do it with more people and explore even more ;)