First off, I live in the US so I don't really know what you guys havei n guitar stores in the UK, I guess the inventory is different because someone (i cant find it now) in this thread said they cant find stores that sell Jazz III picks or Ernie Ball strings, and in the US its hard NOT to find them
anyways, here goes
1. Stock brands that you cant really get anywhere else, i.e. there is 1 retailer for Caparison in the US, and I desperately want to try one, but I cant. Same thing with ENGL. Most of the stores here stock like Crate, Fender, Marshall, Line6, Vox, and thats it. I think you would make some real money if you were the only retailer of brands like Tagima and LAG around. My favorite guitars tore of the area doesnt exactly stock uncommon brands, but they do stock higher end guitars, and they stock a lot of amps you cant get elsewhere (Laneys, Peaveys, Mesas, and a lot of other brands)
2. Stock beginner stuff, and high end stuff, forget the middle of the line. Here there are only really 2 big guitar chains, Guitar Center, and Sam Ash. 90% of guitar centers guitars cost 500 dollars and it really pisses me off. I think it would be nice to go to a guitar store that stocks real ESPs (not LTDs), USA Select series Jacksons like the sl1 soloists,
3. Make sure the guitars are set up good. I went into a guitar shop once, and one of the sales managers handed me this RG Prestige 2550, I wasnt even looking to buy a guitar, but it felt so nice and has such a good setup that I bought it on the spot. (it was used by the way)
4. One thing I hate is when I go into a guitar store and the staff is really pushy. Most stores here you walk in and like 3 guys follow you around asking you what you are looking to buy, it gets irritating.
But I don't know anything about business :P those are just a few things that would keep me going back to the same store