Those who have participated in some form of Ethical non-monogamy, what tips and advice would you have for a couple trying it out?

My wife and I aren't exactly going down this path, but we have had a lot of discussion about our viewpoints on this topic and there's nothing really standing in the way of us exploring engaging with others.

I'm defining ENM as any sexual interaction outside of the marriage where all parties are aware and giving explicit and continual consent to the interaction. Could be open marriage, threesome, swinging, etc.