How do I improve image.?

[Bren C]

Ok, I'm known as the crazy(not the bad way),funny ,random, childish, irritating to some type of kid. I have been going to the same school since 3rd grade and I've went from silly-wierd-lame-funny throughtout life. They're some people I just can't help but act this way around because I'm comfortable around them.I'm now a sophomore and I want to change myself image, but basically my image in general. I want to mellow out a bit, be a bit more cool and collected and confident but still be myself and comfortable around peoplp. What are some tips, advice, motivation etc to change myself