well you first have to have stuff in common. like sports, beliefs, etc. then your friendship just builds over time.
try to become friends with that person that your best friend is friends with. MAybe you can become a trio.
try to become friends with the other person too
You don't!
Become close friends with someone- build a mutual trust/respect/loyalty to eachother, hang out whenever possible doing things that interests you both
they love each other and hanging out
you wouldn't just become best friends with her, you'll need to know her and not just be a stranger or anything besides she already has loads of best friends
Usually it is best to become friends with someone before expecting a kiss.
It's not as easyas buy them lunch one tiime and then your best friends. It takes time, i used to be like you... i had been kicked out of popularity and had noone, but you have to stay faithful and gradually start trying to hang out with them. over the last 3 weeks i have become better and better friends with someone, but still we're only just friends. i hope to become his best friend and if you take it slow gradually start chatting with someone you'll soon be close.
make friends with someone you like then show that them you are really interested in them.
Try befriending that person and if that works, you may become best friends. Then that person will have strong feelings for you.
Become friends.
Become close friends with him\her.