I don't think what you are talking about is limited to FTT. Any participation in either the lifestyle or seeing a Pro Domme has generally the same risks and fears for most people since the public doesn't really distinguish between the activities within our world. The fact is that if your partner is untrustworthy and wishes to blackmail you, it doesn't matter if you actually did FTT... all She has to say is that that you did (unless your fear is only that you actually did it and other people know vs. everyone thinking you did it and you knowing its not true). So, as long as you are willing to see a Domme the same rules apply.

Its all about identifying and choosing someone who is trustworthy on a personal level. You can do an NDA with a Domme but that means you have to give them your personal information and that really opens you up to the things you are most paranoid about. The fact is that if someone is a well-established working Pro Domme their business can be destroyed by an accusation they are not trustworthy so they have a lot more to lose than they will gain.

As for the general internet, if you are truly paranoid then you never give out your personal information or allow a photograph of you to be taken that is attached to your online identity. Even more paranoid, don't use the same devices to use apps or access sites for both your online and legal identity. "Accidents" happen because a desire for convenience makes someone sloppy.

However, being outed almost always happens because you pissed the wrong person off or you go to see someone who doesn't deserve your trust (generally because you are listening to your crotch rather than paying a professional rate for a true Pro after doing proper research to find someone who is worth trusting) rather than an "accident".