Advice for a first time threesome?

So my husband and I have been having some rough times lately. Mainly with things getting too “routine”. So I brought up the idea of having a threesome the other night, at first he was against it but now he’s so excited to try it. It would be MFM, with one of his best friends. It would be my first time doing a threesome but not theirs (Not with each other).

So any tips and tricks to make this experience amazing for all of us?

I hope it happens, I’m just so nervous but excited😬😋