Inexperienced girls require you to move slightly more slowly to ramp up comfort; however, you cannot move so slowly that you lose attraction.
This means establishing baseline accidental touching more often. It seems you made the touching seem purposeful by lingering there a bit too long, and ideally you'd pull away first.
Your particular story brings me back to a time when I was first exploring flirting (before girls chase). I'd try all types of "touches" on a girl, almost always in a computer class of ours where no one really noticed them. I usually would do things like poke her pressure points, but occasionally I tried light stroking of her hand, which usually caused her to pull back. I understand now how that didn't feel right for her; "Here we are in public and this guy is lightly caressing me, something that's usually done in private! Eject!" was probably her line of thought.
Eventually she became comfortable with my touch and I learned not to do those types of things. She probably would have became comfortable much faster had I kept things limited to accidental touching, or brief teasing such as poking her pressure points, rather than awkward touches. This is something you simply need experience with to know when the situation is right.
Using compression date templates, which I typically do with more inexperienced girls, it'd look like this,
Dinner - "Accidental" grazing of feet under table, kiss at end.
Physical activity next morning - Purposeful physical teasing, lightly pushing her
Dinner at my place that night - Go for lay.
