M.6.
Our daughter was socially shy. She had one friend that she stuck to like glue and unfortunately that friend often manipulated our daughter emotionally (would tell her she didn't like her or hang with other friends and exclude daughter, etc.). The friend didn't have a great home situation so it was understandable that she was taking control in areas she felt like she could since she had no control at home, but still, my daughter was the one who ended up crying many times over this friend's behavior, but was still too "shy/uncomfortable/awkward" at starting new friendships. Additionally, this "friend" kind of tainted other potential friendships our daughter could have with other girls either by telling those girls things that weren't true or telling my daughter she would no longer be friends with her if she was friends with so and so. Ugh - it was pretty rough and hard not to get involved.
What we did was we enrolled her in modeling school. Yep, sounds crazy, but it was AMAZING. The whole point of modeling is to be outwardly confident about how you look and feel. She had to learn to speak in front of other people, walk confidently, talk confidently, and she did auditions for different places which really helped her social confidence. The folks that ran the school were professionals in getting kids to really play on their strongest points and minimize the areas they were less confident in. My daughter blossomed into an amazingly confident young lady - so much so that she decided to move to Sweden for a year during high school and go to school. Something I never, ever in my wildest dreams would have ever considered her doing in my life prior to that. She now is in advertising and gives pitches on a daily basis.
This might not be the answer for your daughter, and I'm not going to lie, it wasn't cheap, but man when I think back to the shy little 13/14/15 year old she was and then the huge change, it was worth every penny!