As an ISFP, myself, I prefer to keep conversations light and to know what others think before feeling secure about telling my own. So try not to get too close too soon. For me, that's a huge turn off-- for me, I'm unsure about others, but it is especially when you show you're desperate.
ISFP are about building bonds, so if you're going to jump straight into a relationship, that's a huge turn off as well. We don't like shallow thinking like that; we like to build relationships one step at a time. And we prefer to go at our own pace, and we're pretty stubborn at that (and I say it's different from procastination jussayin')
Unsure about others, but if you pay attention to her a lot and get to know her mannerisms, what she prefers, doesn't prefer, and basically show that you're mindful, she'll notice the subtle and genuine interest. Other wise you'll scare her off if you're not focused on her preferences: i.e. soft voice, calm environment, light topics, etc.

Hope it helps