Brandishing is a term usually reserved for deliberately drawing the weapon and waving it around. I think what you mean is "flashing".
Sure, who hasn't?
In some states, even a brief couple of seconds look at your holstered gun can get you in a lot of trouble. In other states, it's ok to accidentally expose it. In SC, you can accidentally expose it if "an effort is being made to conceal". You can show it when transferring it from a holster to a glove compartment, let's say. Didn't used to be this way, used to be a lot tighter.
"Printing" is another matter. Again, the law differs from state to state. At times, almost any carry method will print, but usually all you see is a rectangular or roundish outline of the butt. Is it identifiable as a gun? Most times, it isn't.
How to prevent flashing? You don't have to worry about your weapon constantly, but you do need to be aware of it. The more you wear it concealed, the better you will become at concealing. You will subconsciously avoid raising that arm and will protect that side from being bumped. It will become automatic (no pun intended).
You will learn which shirts/jackets conceal the best. You will learn, as others have said, to dress around the gun.
As I've said in the past...of the ten people who will see your weapon:
Eight will think you're some type of LEO.
One will be a BG who suddenly decides this isn't the day to stick up McDonald's.
One will be another carrier who will smile and say to himself, "Today, I am not alone."
Occasionally, you will run across the jerk who wants to be a big man for his SO or thinks his opinions are the law of the land, and he'll try to make an issue of your gun. Deflect his comments and objections calmly and quietly. Don't argue or get into a scene. If you're in a store where your weapon is allowed, call the manager and tell him you're being harassed. If you need to, call the police. He's inciting and his manner could be considered threatening.