As for buying any new club, try before you buy.
When it comes to fitting, always get
clubs fitted to you. The difference depends on how far off 'standard' you are. If you have been playing with off the rack
clubs and you are 6'5", you current
clubs are probably too short (you will need to bend over too much) and too flat (your ditots will be deeper at the toe of your club). What this means is you have hand to adjust your stance to fit the
clubs, therefor not being as efficient as possible. This will also cause a much more steep attack plane, creating a swing that has a tendancy to slice.
On the other hand, you are 5'3", the
clubs are too long and upright, causig you to stand too upright and not flat enough causing a heel divot and a very shallow swing, which can be a culprit of a hook.
It will take a while to adjust to custom
clubs is you are quite a way off standard. If this is the case, it would be best to visit a pro to get you on the right track because it will really feel foreign to you for the first 200 balls or so.