Concealed carry is mostly about common sense.
It might be worth your time to hang out in your car in the parking lot of a store like Academy, Scheels, Gander Mountain, Cabelas, or Bass Pro Shop where they sell firearms and reloading supplies. These are places that tend to congregate people who conceal carry as many of them are also avid shooters. You'll see the same folks at Walmart or the local grocery store, they are just more highly concentrated in stores that sell guns, ammo and reloading supplies.
In any case, observe people getting out of their vehicles and walking to the door. Here are the things you'll see that will loudly announce "I'm conceal carrying".
1) checking his shirt when you get out of the vehicle and in particular checking one side and not the other (usually right side as 80% of people are right handed).
2) checking his shirt once or twice more on the way into the store.
Bonus points to the guy who looks around to see if anyone noticed him checking his shirt 3 times (feel free to give him a friendly wave when he looks your way.
4) dressing unseasonably warm for the weather just to have cover garment.
5) wearing one of those tactical, photographer or fisherman style vests (unless of course he looks like an actual fly fisherman).
6) dressing like an "operator" complete with logo'd ball cap or t-shirt with a punisher graphic or some sort of tactic-cool graphic. Bonus points for the instructor belt. More bonus points for the slow scan for threats as he walks from car to store. Odds are that guy is carrying even if you don't see any signs of the gun.
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After you've figured out some of the more obvious ways not to dress and act by observing the parking lot and the door, go inside as that can be just as educational.
At close range, if you are looking for them, you'll spot the belt loops and belt clips of IWB tuckable holsters where the shirt is tucked in over the handgun. Also note that even though you know what's lurking underneath, no one else is noticing or caring. For example, I was in an elevator once and had a lady ask about the metal belt clip for my IWB holster. She was curios, not suspicious and I told her it was for my TENS unit and we had a nice elevator conversation about back pain. That's the one and only time any one ever remarked on it (I've been conceal carrying for 31 years), and having a ready explanation avoided having a conversation about concealed carry, and would have also covered any visible bulge.
Most people don't go around staring at people's belts. The few folks that see a belt clip or belt loop, won't think twice about it - unless they also conceal carry, or live with someone who conceal carries, and in either case they won't care that you are conceal carrying.
If you look around for people with un tucked shirts and look closely you'll probably spot some folks conceal carrying due to a slight bulge, or perhaps a harder edge printing now and then. Also note that no one is freaking out about that either. The vast majority of people are not going to notice a slight print, particularly if you look like a normal person rather than a potential threat.
There are limits however. The other day I was in a store and I noted an averaged over weight middle aged white guy with an average hair cut and no beard wearing shorts and a polo shirt with an average looking 6 or 7 year old kid beside him. All pretty normal, except he was standing in the gun section of the store looking at handgun ammunition, which prompted me to look at his waistline. Low and behold there was an incredibly obvious bulge under his short caused by his tactical tupperware Kydex OWB holster holding what appeared to be a Glock, based on the shape of the grip printing through the shirt.
I suspect he was fairly new at the whole concealed carry thing. I hope he also shopped two isles down where they had an ample selection of IWB holsters, and also took the time to look at some of their Magellan and Columbia short sleeve shirts that also look nice untucked, are loose enough fitting to fully conceal your handgun, and don't look out of place around town in the summer.
I own a half dozen of those and the fit in well in eastern NC in the summer months. In the winter, I lean more toward my western roots and tend to dress in western boots, jeans, long sleeve shirt, western vest and hat. Even eastern NC has its share of cowboy and ranch types and it's not out of place. The vest covers the handgun, and if people notice anything it's the boots, vest and hat. I get lots of appreciative comments on the boots and hat. No one notices the 2.5" Model 66 or 2.5" 686+ I normally carry in the winter months.
There's no such thing as perfect concealed carry, and there is no one size fits all answer. But you'll seldom go wrong if you dress the way other people around you dress, dress appropriately for the weather, avoid looking like a walking advertisement for 5.11 Tactical, and take care not to do things that suggest you might be carrying a handgun - and the key to that is to not obsess about it. That'll get easier after with time and after a year or two you'll stop thinking about it entirely.
