No one should know you are carrying unless you tell them.
Be ready to commit to training both with your weapon of choice and your carry accessory
Wear your holster or carry accessory around the house so you get used to it
Always, always, always practice firearm safety
Always know and follow the laws of where you live and where you are going
Remember you can’t carry eveywhere, check first
The best way to avoid potentially dangerous situations is to be situationally aware and avoid them. Your brain is a much more powerful weapon than any gun you can carry; if you see or are in a situation developing with escalating threat, get out and call the police.
If you’re worried someone will see it, dress differently. If it’s uncomfortable, deal with it, or go into a restroom where you have privacy, and re-adjust your rig until you are comfortable. By fiddling with your gun nobody can see, they’re seeing you act suspicious with something hidden under your shirt – and THAT will raise alarms.
IN AN ACTIVE SHOOTER SITUATION, EVERYONE WHO IS NOT A POLICE OFFICER AND HAS A GUN IS A BAD GUY. When the police get there they have mere seconds to assess the situation if you are not Police and have a weapon, the Police can’t tell if you are the bad guy or not.
Invest in the right weapon and carry rig. Remember you are going to carry every day, quality is important.