Don't curse. Having a foul mouth is just not classy at all. If you have the urge to curse, go into the bathroom and turn on the faucet while you let loose a row of expletives; or curse into a pillow. Never let people see you curse. This will often make you look trashy, and if you're cursing because you're angry, it appears as though you don't know how to control your temper. This is a big sign of having no class.