Just kidding, don't do it.
Seriously though, I have found that holster choice makes all the difference with IWB carry, and I've wound up purchasing several until I found the two that work the best for me right now. And since I am left handed, I actually have fewer choices than most people, but I still was able to eventually find the right holsters. Because of my (very attractive) "love handles," OWB carry makes both my pistols stick out too far from my side to easily conceal. Thus, some manner of IWB or pocket carry are my main realistic choices.
My first holster purchase was was an OWB paddle from Fobus for my USP Compact. That didn't work, but fortunately, it was only about $25.00. If anybody wants a left handed Fobus OWB paddle for cheap that fits a USP Compact .40, let me know. My second purchase was a Galco Summer Comfort IWB holster for the same pistol. My third purchase was a custom made kydex IWB for my Commander sized Sig 1911. I no longer own that pistol, but I kept the holster, which did work well, for the day that I buy another Commander sized 1911. My fourth purchase was a D.M. Bullard IWB holster for my 3" Kimber. It is a beautiful piece of work. Really a nice holster. Unfortunately, after a few weeks of using it, it positions the pistol up too high for my dreaded "love handles," and the holster moves around too much. I've lost 39 pounds this year already with Weight Watchers, so I'm keeping that holster against the day that I will be able to wear it closer in to my body. My last purchase was a Galco Royal Guard IWB for the Kimber. It is perfect.
The thing that both the Galcos and the custom kydex holsters all have in common is that they position the pistol lower down inside the belt so that they are firmly retained and do not stick out. Although I don't wear extremely tight fitting clothing, neither do I wear extremely baggy clothing, and even "business casual" attire conceals both pistols effectively with shirt untucked. In fact, the USP Compact, which is the larger of the two pistols, actually conceals more effectively than does the Kimber, because the USP, with its longer frame and barrel, carries its weight (and center of gravity) a little lower down behind the belt line than the Kimber.
FWIW, nothing screams "Man with a gun!" like a fanny pack. I would avoid that one like the plague. It just makes you into a target. If you're going to carry a small, light, smaller caliber pistol, try something like this holster if you are really concerned about attire.
Finally, one thing you haven't mentioned in all of this, and which you ought to consider, is how you are going to carry either a backup magazine, or speed loader if you're going to carry a revolver. Granted, if things go sour enough that you have to deploy your weapon and fire it, statistics say that you'll probably not have to fire more than 2-3 shots. But if it goes downhill from there, you're really going to wish that you had planned for that extra ammo.