Know your limits, and make sure your playmates know theirs.
Ironic as it may seem, if you're going about your affair with any sort of intent, you need to understand and respect your level of commitment to it.
Don't over commit yourself
This is the easier mistake to make, particularly when you're first getting involved with someone. You want to make the best of a good thing, and certainly don't want to disappoint your new playmate by turning down an offer for a slutty rendezvous, handjob breakfast, or a weekend in the Hamptons.
The problem comes when you have every intention of making something happen, but the rest of your life gets in the way, and you have to flake - usually at the last minute. So be realistic about how and when you can get together, and put that on the table. Sure, there's every chance your new 27 year old fuckmate with nothing else to do on a Friday night may be disappointed. May go fuck one of her just-barely-out-of-the-frat friends instead of waiting for you.
First of all, remind yourself that there are worse consequences than that. Then remind yourself that in order to play safe, you're playing smart. One too many "stuck at the office again" excuses on a Friday night is the stupid way to go about fucking around.
Be honest with yourself, at the very least, about what sort of time you can give to a fuckfriend.
The heart wants what it wants.
This is the other kind of commitment that we need to talk about, and it's the harder of the two in terms of quantifying and in moderating. So let's get something out of the way: Unless you're a douchebag automaton, you're going to get emotionally involved with your playmate. If "involved" gives you hives, then try "entangled".
This is one of the consequences we talked about earlier, and remember what I said then: if you're fucking someone who doesn't appreciate the fact that there are consequences - run, don't walk. This person is going to step on your life eventually. Involvement is wholly natural, entirely expected, and possibly unwanted. That works fine if you’re both in the same place: if all that both of you want is to screw each other into oblivion, so be it. Problems arise when one of you wants to get in deeper and the other doesn’t.
All that said, you need to be very fucking honest with yourself about how deep down the rabbit hole you're ultimately willing to go with someone. Naturally, this might change on contact with someone new - but knowing the baseline is important.
Discretion and Limits
Another limitation that She and I have come up against in our fuckery are the boundaries set by discretion, and the desire for anonymity. Not wanting to be seen in public with your playmate (or them not wanting to chance being seen with you) can set limits on what you can do together, and ultimately may set a limit on the lifespan of the fun and games.
While absolutely destroying the linens in a hotel room is most assuredly something I applaud, there's usually more to the desire to screw around than just the need for a new shape and size of cock, or the willingness to take it up the ass. The best sex always comes with an emotional payload, sorry to say, and you can't build that charge up with just oral expertise. Other shared experiences build the argot of passion that is then expressed during sex. The brain is the most important sex organ, and shouldn’t be discounted.