concealment models, styles...
For the general concealed carry market, I'd suggest small powerful DA only revolvers & semi auto pistols.
Top brands like HK-USA, SIG-Sauer, S&W, Ruger, Beretta, Glock, CZ, Springfield-Armory.
New designs like Ruger's LCR revolvers, S&W's Bodyguard .380acp & .38spl(with Insight laser aimers). The SIG Sauer DAK P229/P239 would work well. The compact HK P2000/P2000sk LEM designs & the Beretta PX4 C or subcompact 9mm/.40S&W conceal well.
Compact Glock, XD and Kahr models could be popular too.
I'd stock well made self defense/carry ammunition too; Winchester Ranger T, Speer Gold Dot, Corbon DPX, Buffalo Bore, Hornady Critical Defense-TAP, Magsafe. Quality pistol/handgun rounds are hard to find and you should endorse-sell high quality brands.
Cleaning products; Mpro7-LPX, Weaponshield, Gunzilla, Eezox, Hoppes #9, Boresnake Vipers, Otis kits, etc should be stocking items also.
Too many gun shops & FFL retailers want to make a quick buck and treat gun owners/shooting sports-2A supporters like dirt.
Learn & understand the industry. Train your sales staff and clerks.