How about a shy young woman, 18 years old and just starting college, being introduced to erotic tickling by a slightly older (but much more experienced) woman who lives in the same dorm.
Just take your time, and let the ideas flow. It ain't easy writing a story, but the good news is that whatever ideas you may have - since there is a huge amount of people interested in the story section of this website - you'll have fans of no matter what you write (within reason). Later.