the second makes more sense

Basically, both phrases mean the same thing – that you think someone is beautiful. But "for me" shows it's your own opinion, like your taste, and "to me" means the person has qualities that most people would agree are beautiful

The first one doesn't really make sense. The second one is another way of saying, "I think she's beautiful."

The second is more common. It means that to you she seems beautiful. It sounds better if you say "To me, she's beautiful". The first is quite uncommon. I would interpret it to mean that she has made herself beautiful to please you. It sounds rather conceited. If that is what you want to say, it would be more clear to write "She has made herself beautiful for me".