fastest free way? just play 18 hole rounds all day long,
and multiple player rounds, preferably 4 player rounds.
try to play well, that way you'll win all these dumb awards that mean nothing,
but you'll get some extra XP points for them.
if you really wanna cut in line, you can buy your way out of the normal process.
go to accessories in the pro shop, and buy a bunch of level up bars,
until you hit 64, then you buy the 40% XP drink for as long as you can afford (15 days max)
and just plow through 18 hole rounds as much as possible.
I'd suggest neither.
the long slow process of playing with the free crappy clubs,
will cause you to develop a good feel for the game,
since they provide zero spin, thus forcing you to be more accurate with your shots.
I know the clubs in pro shop look awesome, and they are,
but the process is a big part of becoming a good player IMO.
cause when you finally reach that level where you can unlock the good stuff,
you'll be much more ready for them - and you'll cut your avg in half almost overnight.
either way, good luck.