The thing to remember about letting someone know about this, is that it depends a lot on the person most of the time. There are girls who I have been open with about it, and frankly, they think it's awsome and sexy, it's just a part of me. Then there are others who kind of feel uneasy about it, uncomfortable, when I'm open around them, to them, anything. If you know the person well enough, you should know if they take things as they are, accept things, or if they are catious. Being open is faster...but not always the best choice. To play it safe, I suggest you do the following.
Every once in a while, sneak a quick tickle in, nothing special, just a friendly tickle, I mean, everyone knows that friends often tickle each other off and on SOMETIMES, it's nothing akward. If she reacts and doesnt mind...you could slowly but surely do it more often. If you arn't getting a good vibe, best choice is to back off and try with someone else. If you don't get the initial acceptance, you don't get anything more.
After you have started being more frequent about tickling her, she will obviously start to notice you like it. From experience and what I've heard, at that point, they will decide if they're going to let you continue. If they start to avoid it, back off...maybe start with being casual about it again, maybe try to work your way back into it. If you stop getting a good response, then it's time to stop.
But if she continues to let you tickle more frequently, you might want to start doing more, maybe pinning her down and tickling the crap outta her for a minute or something. If you continue to get good responses, after a while, you'll want to tell her, although she will probably have figured it out by then. Most girls don't have a problem with it, and if you've gotten to that point, then they don't mind if you continue to tickle them. That would be your oppertunity to ask.
-end of rant.
😀
Just my opinion though 😉
Oh, as far as my ticklee goes, I found her by being 100% open with her. I gave her any information about it she asked for. I asked her if she thought it was weird or anything and she just said "Nah, it's just the way you are, I'm fine with it." I started tickling her quite frequently indeed, and eventually I asked her if she would be my ticklee, she just giggled and said "Sure, why not?" Glad I found such an understanding person when I expected ridicule 🙂