A lot of good talking points and advice here, but for optimal concealment, you really do have to figure out what works best for your body type. Something that works great for others, simply may be unworkable for you. For example, I'm short waisted and appendix carry is a challenge for me when I'm seated. I'm also wider through the shoulders and lats and creates natural draping around the waist, and even with the more current cut of clothing that my better half thinks I need to wear. Contrary to Robz caution, I can get away with both thinner material and fitted shirts. Though I do have to be mindful to give a subtle tug on my shirt tail after being seated, in order to be sure my shirt hasn't wedged it self between the gun butt and my under shirt or bare skin.
I like to play gun spotting when out and about and have to say, I notice the baggy clothed guy that looks like he's hiding something more than the guy in more tailored clothes. The 'grey man' learns to blend and wearing baggy clothes in certain settings may get you more noticed than if you look you got the fashion memo post 2000.
The Shield lets me get away with wearing current clothing and not printing. I'm using a Brommeland Max Con-V carried around 3:30-4:00. This is an all-leather IWB with snap loops fore an aft with no reinforced mouth. It is extremely thin [the Sticky holster I have is far thicker], and is canted a bit more than most, and features an extension of leather that curves around the sciatic nerve. This keeps it from digging in and displaces the pressure over a broader area, and perhaps most importantly, works to push the butt of the gun inward. Short pistols carried IWB have a tendency to want to roll outward and this extension prevents that.
Shirt tucked out and the Shield just disappears. There is a magic spot where you get it slightly back of the hip point and the curve of the waist hides it from front bulging and the butt hide in the hollow where the back meets the waist. I carry the flush mags only and find I can get a better grip with just two fingers on the smaller circumference Shield mag well (I wear glove size XL), then when I use the extended mags and my pinky prevents the middle and ring finger from wrapping all the way around. The Shield with the Brommeland holster is the biggest auto I can carry with today's style of tailored casual clothing, and I believe it allows me to better blend, in certain social settings, than the guy with obviously over-sized clothing.
Jeans buying tip: watch out for the lowrise cuts that are popular now. Most holster that are molded to the curve of your hip work less well when the waistband is sitting lower. Frankly, drives me nuts when my pants feel like they are going to fall down, and adding extra weight on the waistband only makes the feeling worse still. Absolutely hate these ladies jeans they're trying to sell us. You can find the same basic current cut, with the narrower leg opening and more tailored overall fit, with a longer rise that allow the pants to sit on the waist. I've had good luck with Banana Republic "straight" jeans. Don't mistakenly buy the "vintage straight" model as they are lower rise. You can almost always get 40% off on a Wednesday with their revolving sales. Don't buy your jeans online - go to the store and bring your gun and holster to try it out - in the dressing rooms with the door closed.
As other have said: a real gun belt is a must. Crossbreed has an interesting one that has no buckle, just a hook to go in the hole. Very low profile belt that is popular with appendix carry guys, but is also cleaner looking under more closely fitted clothing. A giant buckle that screams heavy duty belt (to support a gun) can be a 'tell' for those that are looking for it. Crossbreed also has a velcro lining option for their belts, which when used with their special tuckable clips, eliminates the 'tell' that occurs when you see a bloused out, tucked in, shirt surrounding a noticeable bulge at 3:00 and couple of plastic clips on either side of it.
