play a few rounds...see what clubs you hit the most. improve those first.
such as...you'd be much better off investing in a 3w before a driver...might only look like a few extra yards if you were to hit it off the tee, but you're gaining a ton on 2nd shots with it since you can hit it from the fairway/rough and a driver you can only hit from the tees.
you will lose out on fairways hit stats...but for the added forgiveness and accuracy pays for it's self several times over. will also free up room for an extra wedge or so when the time comes for it.