Fit - Golf clubs, from the putter to the driver, should be a good fit for the golfer. They should have the correct lie, length, and swing weight. They should also have the correct shaft flex, kick point, shaft material and MOI. Individual handicaps will also be a factor, as clubs are made for different skill levels. Always make sure the purchase is well-researched before buying.
The Seller - Online golf retailers often have the best prices on golf equipment. The main drawback to the online golf-shopping experience is lack of experience. In other words, a buyer can't see, feel and experience the club(s). To offset that negative, some retailers offer an exchange or refund policy for a short time. This "trial period" allows the golfer to do after purchase what traditional shops offer prior to purchase.
Traditional retailers, such as pro shops, off-course golf shops, and sporting goods stores, offer the advantage of professional advice and information about the clubs. Some also offer club-fitting, golf club grips installation, re-shafting and other amenities that most online sellers cannot.
Shipping - Even if a set of irons is deeply discounted at an online golf store, the cost of shipping golf clubs may negate any savings. It seems obvious to consider, but lots of people fail to recognize golf club shipping. If you're going to buy online, or special order clubs from a brick-and-mortar store, shop around for the best shipping deals. Some club sellers offer discounted shipping or ship golf clubs for free from time-to-time.
Manufacturer Replacement Policies - Some golf club makers are well known for being reasonable when their golf club malfunctions or breaks. Most will require the customer to send all pieces of the broken club and then send the replacement. Some will send a replacement and require the customer to then send the damaged golf club. Before buying new clubs, call the customer service center of the brand you are buying and learn their policies.
Consider Used or Closeout Clubs. After a club has been used, whether tested by hitting only a few shots or played for several rounds, it must be sold as used. It should also be sold at a discounted price, although that decision lies with the seller. A willingness to settle for slightly used golf clubs can result in big savings.
It's hard to resist the brand new models that come out every spring. Sellers know this and they charge a premium for the new models, while last year's models are sold at often deeply discounted closeout prices. What was a $400 driver the year before may be a $200 driver the next year.