That's a good question because I don't think anyone has a good answer for that. Obviously the only way to totally protect yourself or anyone else is by abstaining from sexual activity... but how realistic is that?

As for warts... it's next to impossible to know if you have a strain that can lead to them unless you have a breakout. The doctors wouldn't be able to diagnose it without visible symptoms being present. Warts generally tend to show up about a month or so after contracting a strain that causes them, but it can lie dormant for so long before showing up, if at all.

I'd say the most you can do, other than abstinence, is talk with your partner about sexual histories, HPV and the risks of infections so that you're both aware of them. Do lots of reading and talk to each other about the facts, such as not being able to be sure the other person is carrying a strain of it. That way you'll at least both know lots about it and can make your decisions based on that. And if necessary, if your partner is female, she can always look into the vaccination which will at least protect her against the four major strains of it.

It's difficult for men since they don't have the option of the vaccination quite yet, and because symptoms are less frequent in them. Since it's rare in men that the strains that cause cancer ever actually lead to it, they almost never know that they even have it.