Why do you want to transplant it?
If its doing well I wouldn't mess with it since replanting can put the plant into shock.
But if you insist on doing it I recommend popping the plant and the dirt (soil or medium, whatever you wanna call it) all out at once so you don't disturb the roots then put the whole thing in a new pot.
I usually use 60% peat ~ 40% perlite. some do 50~50 or mix sand instead of perlite. Personally I dont like using sand its too darn heavy and I cant help but think that its squooshing the roots
although I'm told it doesnt.