As the title says, I don't have a problem as coming off as the "nice guy", in contrary, I need to be attentive as hell not to cross the border between teasing and just being plain mean.

Now, lately I crossed the border saying something as a joke to a really cute girl and judging by her reaction it seems to have upset her very much. Which is awful. Because by "really cute" I mean the hottest girl on my campus, who showed her interest to me already.

Anyway, I did not post here to whine. I wanted to ask you peeps what you would suggest to prevent further happenings like this - I got the "push"-part figured, but sometimes I miss the "pull" - and happen to push them too far. Any help appreciated