I think the main problem many of us are having is all about the equipment for levels. As it was written earlier you can level for ranked rounds, difficult shots and member intereraction.
Reading that, I think all I need to do is play and finish ranked rounds. Very simple to do, free tourneys, unlimited play tourneys, ranked single or multiplayer play. That leaves the door to wide open for sandbaggers, unless you are going to have some sort of checks and balances on the scores.
Difficult shots. Same story, people play CTTH over and over and over and have mastered certain shots and skills. Your sandbaggers dream.
Member interaction. More needs to be developed on this, but so someone with a load of friends, or posts a ton on the forums, or plays a lot of MP games can level up.
All these things are too easy to manipulate.
You need more stats in this game. Single Play tourney + RG + Premium tourney combined average, regular ranked average, and match play stats. If you implement those you have a better way of ranking players, and a better way to examine of possible cheat (yes Sandbagging is cheating, its manipulating the system for a beneficial outcome intended to gain advantage against other players). If you are not going to do that, allow anyone to buy any clubs, but make the clubs related to a tee box.