As for giving free advice, yes, people will undervalue it if you just go around handing it out. I used to do that. However, I learned to keep my advice and opinions to myself until I make a connection to someone (it doesn't have to be deep) and then if they are truly looking for help then I will offer my advice, but as suggestions, not as something they need to do. People like making their own decisions and are more open to suggestions.
This quality, objectively seeing other people, is ESSENTIAL for INFP's to develop.