That is a correct usage and uses a comma: "Being her friend, I am impressed with her helpful nature." "Being an avid reader, I'm always looking for new books." If "being" is a noun at the beginning of a sentence, there is no comma: "Being a teacher is very rewarding."

1. "Being her friend I am impressed by her helpful nature" You can always change "being" to "as" (since your friendship is an ongoing process) to look like: 2. "As her friend I am impressed by her helpful nature." If you are trying to prove that you are impressed by your friend's helpful nature, then "as" denotes that you are her friend and therefore, qualified to make an assertion based on your viewpoint. "Being" is more process oriented and generally expresses someones state of mind such as: "I am being good" or "he is being good" etc. Hope this helps. V/r, Gunner

Using the ing form is not grammatical in this case.