When I was a little girl my father always said," to thine self be true if you can't be true to yourself who can you be true to"!
It's not hard to be nice. Being nice don't mean being blind or being a fool.
When you FIRST notice or sense something, back off to get a better look and size up the person, group or situation so you can think about how or whether to proceed. By all means go slow, keep your eyes open and "Keep It Real/Be True To Thine Self"!
We make our own reality so realize you will make mistakes, don't be so hard on yourself and learn from it.