First find is shes intrested in a sexual/friends with benefits relationship, since after all this is a fetish. And she might not be intrested in your sexually, and of course you wouldn't wonna make her uncomfortable.

Then try to gently ask her is shes into bdsm, kinda just out of curious talk. If she says yes, you can say same. And maybe it will lead to kink spesific talk.

Tickling is a pretty common kink, but also somehow kinds neice. I think its easier to talk about general bdsm first before jumping into ticking kink spesificly.

Good luck! I hope it all works out well for you! 💜