First things first - Do not swing unless you and your partner have discussed rules and boundaries. These must be agreed upon and followed every time you are with another couple. (or other swinging scenario)
Always use condoms! Always! No excuses!
Don't "take one for the team". For those who are not familiar with the terminology, that means that if you both don't agree on sexual parntners for any reason, don't go through with it just to please your partner.
Trust your gut instincts about people you are meeting for the first time. If it doesn't feel right, don't do it.
Work out jealousy issues first. If you don't, these issues will come up after you start your swinging lifestyle. They can and have destroyed marriages and committed relationships.
Do it for the right reasons. Don't try to fix your marital problems with swinging. It is for people with healthy, trusting relationships only.
Know that it is ok. You are an adult and have the right to live however you choose, as long as nobody gets hurt.
Never meet new people alone. I shouldn't have to explain why.
Do Not trust that just because your potential partners say they have been "fixed" or are disease free, that they are telling the truth. There are bad people out there, and trust should be earned.... not given blindly.