how can i get 300 qi realy fast?

Buy it in the shop. Or get a Qi booster. They're the physically fastest ways.

Play in a normal server with less people in it.
Beat people try not to loose.
Don't try tourney rooms, or private rooms or rooms with too many people in it.

which shop bro? and whats the name?

Now hampa was launched ToriBoosters for person who can get black belt

look at hampa's signatures

Go to shop then look at the left hand side or here

http://forum.toribash.com/tori_boosters.php