What can I do when my best friend copies everything I do?

well i think if u are in your late 20's and this is truely a best freind then i would say let her know it bothers you and she needs to be her own person

So you are in your late twenties and you still care if someone - your friend - gets it too? So I guess you do not like that she sees virtue in your opinion?

Sounds like you should should dump her. Why have a friend who likes the same things you do and admires your sense of style. Better for you to get a group of friends who secretly talk behind your back about your terrible tastes and how little they think of your opinions. Or maybe you will be lucky enough to find one who will tell you how miserable it is to be you right to your face.

Or

You could just grow up.

Just don't tell her anything that you think she'd copy you on. You can also have a little talk with her, too.

talk to her that she shouldn't be copying you, but don't put it blunt like that. just tell her you don't like it and you liked her much better as her original self who you made friends with.

just don't tell her stuff you don't want her copying. or talk to her about it! just explain that it annoys you how she copies you and you'd appreciate it if she would stop.