Hmmm...
Just tickle them when you are in a situation when everyone is comfortable with each other. See what it leads to and use the information you get back for further tickling encounters.
By information I mean:
1. Who likes and dislikes to be tickled.
2. Who is ticklish and where.
3. What type of conversations does the tickling generate.
4. Who gets into it and who runs from it.
5. Does it motivate them to introduce tickling in the future.
There is a lot that you can get out of this if you do it at the right moment.
Do not go around tickling people in a funeral. 😉
Try to do it in a place where everybody is very friendly and acting silly. This way it does not seem out of place.
There is nothing wrong in being seen by your friends as the tickle monters or the guy who likes feet. If it is always done "innocently" in non-controversial situations, it is always a positive experience.
There is no need for them to know that tickling is a fetish and that there are communities like this for people to feel comfortable with the topic. There is still a lot that can be gained from innocent tickling in social interactions.
Now, if you are into heavy stuff, then you are out of luck. Better find people who are into that and go that way. That's a whole different world.
I hope this helps,
Knight Tickler