Don't be negative.
Generally speaking, people stray because of some negative emotion: fear, anger, resentment or loneliness. To some extent, the start of all fucking around is born in a seed of negativity. What you don't want to do - what you shouldn't do - is throw that negativity around like confetti.
Looking for a lover is a positive step, or at least it should be. A fresh start. A new adventure. Of course, there's every likelihood that this relationship will also have its up and downs - that's humanity for you. Starting off on that footing, however, is a sure way to never get started at all. You see it all the time in the profiles and ads that are the common currency of looking for a fuckfriend online: DDF or DDDF, or simply: NO DRAMA.
Let's be honest - does anyone really want the opposite? "Please, come into my life, boil my rabbit and try to skewer me through the testicles!" It's pretty much a given that if someone's going to be a drama queen (or king!), they're not going to advertise it up front. I'LL FUCK UP YOUR LIFE is not a popular title on Craigslist for a reason.
So let's talk about mroe subtle forms of negativity, and how to avoid them in your own communications with your intended cheatmate.
Don't complain about your current situation.
You're in a bar with a woman who looks amazing in that retro dress, can drink and swear you under the table, and whose eyes flash like sapphires when she smiles.
Why the fuck are you spending your time with her complaining about how your wife hasn't given you a decent blowjob in 10 years? Shouldn't you be concentrating on letting her know how goddamn appreciative you'd be if she'd fellate you?
Sure, there's a time and place for discussing your situations - everyone's curious why someone else is out in the field - but don't make it the centerpiece of your conversation, in email and especially not in person.
Don't accuse people of head games.
I've seen this one a couple of times, and so has She. You're corresponding with someone, perhaps at a rapid clip, when someone calls, or you suddenly need to take an extremely urgent shit. Maybe it struck just after you promised to take a picture of your clit and send it Mr. Amazing.
To Mr. Amazing: This isn't a head game. This is life.
If something like this happens: there's a minor break in communications or one missed date/phone call? Fucking relax. Get a drink. Masturbate. There may be a perfectly good reason for what happened, and starting right off the bat with "What, we all done talking?" is a great way to ensure that Ms. Amazing gets the message that you're a bit of a needfreak, and insecure about your ability to hold her attention.
You sent your response to her, so give her a chance to either pick up the thread later, or start a new one. Feel free to send another message during the course of the day or evening, but don't press any points. Just talk like a normal human being.
Of course, people may just drop off the radar as well - such is life. But the fewer messages you send chasing after, the better.
Don't swing your dick.
This is negativity in a more aggressive vein - bragging about your ability to eat pussy and/or your golf handicap, and telling a woman she's guaranteed to scream her head off with you is a form domination: meant to impress, but really beside the point. Usually this comes from overcompensation: your wife doesn't fuck you, and you know you can fuck like John Holmes on crack, so obviously you need to inform everyone who comes along of the point.
Discovery is one of the true joys of screwing around - finding new people to enjoy, and new ways to enjoy them. Starting off with the macho stance (and ladies, I don't mean to leave you out of this discussion - maybe I'll have a note to add from Her after I publish this) stunts that sense of discovery and actually puts you on the defensive - having to live up to something that you could have just quietly surprised your fuckbunny with in the first place.
When you're out looking for a lover, you're starting something new, even if its born out of something old, and possibly some real, honest pain. Dumping that pain on prospects not only doesn't help your case, but builds on the negative spiral. Take each new email, ad response or meeting as a fresh start, and you'll have a much better time of it.