How can I change my personality?

I am shy, paranoid, hot headed and very very absent minded. I try to be nice but I can be very bitchy as well. I don't lie that much. I have crazy mood swings. I am also at times really weird like I blurt out the randomest things by accident! I would like to change my personality..? How could I go about doing that? In particular I hate being paranoid and shy. I want to be a bit more of a loose easygoing person?