I think Greg Tallman has it just about right.
I do think any good private golf shop needs some clubs, otherwise it's a clothing store that happens to be at a golf course. At the very least a handful of drivers, wedges, and a set or two of irons dress the shop up and are conversation pieces to move people around the shop and just pick off a shelf to hold in their hand. If they don't sell during the season, chalk it up to helping sell other items and then get rid of them around wholesale cost at the end of the season - either online, as a tournament prize, or in a big year-end sale. I do agree that the bulk of equipment sales can and should come from demo days, custom fitting, etc. But a golf shop without at least a few golf clubs is not a golf shop.
Logo items are a key, and mix up the accessories. Have some logo essentials year in and year out (the most popular stuff - tumblers, repair tools and other little functional souvenirs, etc) and then mix up the other accessories so they skip a year or two or more - this would be for more specialty items you sell less of, like leather goods, high-end belts, glassware, etc. Keep looking for less expensive accessories you can logo once and then never again unless they go well, like bookmarks, Christmas ornaments, wine stoppers, etc. If they go, great, and if not, it's no big deal.
As far as logo apparel, you have to have the basics in bulk and then dress them up with a few cashmere sweaters, lined wool windsweaters, sweater vests, etc. They help sell the basics and again, if they don't all sell during the season, you can clear them out at a discount at the end of the year.