Too many golfers want to get fitted for new clubs because that's what the salesman or club pro told them to do, or because of some sense that nobody buys "off the rack" anymore. For some, fitted clubs will be money well spent, but others would be better off investing in some lessons first.
The club-fitting process involves both static and dynamic measurements of your golf swing. The goal is to determine what loft, lie angle, shaft flex, head design, length and grips your clubs will need to best suit your game. After the measurements, you will be asked to hit a few shots and maybe try a few irons with different lofts and lies. There will be questions about your playing ability, ball flight, where your miss-hits tend to be and your goals. The club-fitter will offer an opinion about what would be best for you.
You Should Not Be Fitted
The question of whether you should be fitted leads to another: Can you repeat your swing? If the answer is "no," being fitted for clubs should not be your first priority. It's not about how your swing feels; it's about the results. If you consistently hook, slice, pop up or roll your shots, chances are you have a swing that at least reasonably repeats. If you consistently hit shots in different flight patterns--one left, the next right and not on purpose--you probably have trouble repeating your swing. You can't fit a club around your swing if you can't repeat it consistently. You will end up trying to fit your swing around the club. Before spending money in custom-fit golf clubs, invest in lessons from a PGA professional.
You Should Be Fitted
If you can repeat your swing, then you absolutely can benefit from being fitted. If you strike the ball too close to the heel or toe of the club, or the sole bottoms out on the heel or toe, your clubs might be too long or short for you. The fitting process will reveal these problems, and you can have the clubs adjusted so your natural swing will regularly strike the ball on the sweet spot. Having clubs that properly fit your swing can help correct a flaw or poor ball flight without changing your swing. Playing with the right clubs will have an immediate and profound impact on your scoring ability.
Once you have committed to getting custom fitted, consider whether you're feeling good, pressed for time, feeling pressured or swinging poorly. Don't allow any of these factors to interfere. If you are tired, sore or not warmed up, you will not swing the same as you normally would. Don't come straight from work or when you only have a little time, then grab a club and start swinging. Schedule the fitting when you have sufficient time to stretch, warm up and patiently go through the process. Even if you are feeling good, make sure you are hitting the ball like you normally do. You don't want to get fitted on a fluke day of good or bad ball-striking. Usually, the cost of the fitting is subtracted from the cost of the clubs if you buy them. If you don't like any of the clubs you try, then don't buy anything. You will likely have to pay a moderate fee for the fitting, but the results are yours to keep.
Do not forget to get a putter fitted as well--this is the club you use more than any other but the one golfers have fitted least often. You can also be fitted with your current putter and have it adjusted. Golf ball fitting is also available. The amount of choices you see when browsing the golf ball aisles can be overwhelming. Being fitted for a ball will narrow your choices based on your swing speed, spin rate, and ball flight.