I need advice on how to tickle an escort/stranger

I live in Australia where prostitution is legal, and I’ve seen only two escorts. The first one I saw didn’t really let me tickle her and the second one did, although the desired response was rare. She gave me the impression that she wasn’t very ticklish and she was just fake laughing from time to time, but I think it had more to do with the fact that I was a complete stranger to her and tickling of a trusted friend is likely to elicit a stronger tickle response.

I’ve both heard and read stories of clients getting the desired response (smiling while trying not to laugh, giggling and of course laughing) and I just wanna know if there’s something I can do to elicit that reaction out of someone I’m meeting for the first time?

Do I need to converse to make them more comfortable?
Is anything in terms of foreplay that I can do?
Mental tricks or anything like that?

Conversation, and making people feel at ease. you usually need to meet people multiple times to really get them relaxed.

Also when calling for an escort, ask for an actually ticklish one.

If you're already at that level of physical intimacy (regardless of paid or otherwise), I've always felt the easiest thing is to do a single, <1 second poke in the sides, usually at the same time you might say something funny, and gauge her reaction. Whether it's positive, negative or no reaction at all will probably be immediately obvious.

In 100% of my experience, even the girls who absolutely hate being tickled and say so won't hold it against you if you do that once and stop -- assuming you're already being physically intimate with them in other ways. I believe there are a lot of girls who'd be completely fine with that approach, but who would be creeped out by some serious "I am a fetishist" conversation.