I haven't given anyone the finger in traffic for years. It's a habit that was hard to kill. I also quit antagonizing other drivers who behaved rudely.
My response to tailgating is to control the space in front of me. If you're going to be 5 feet behind me, I want a couple hundred yards of free space in front of me.
In a road rage situation, you don't want to have to tell the cops or a judge you gave a guy the finger or hit the brakes in front of him, and then he went nuts for "no reason." Cops, judges, prosecutors, and juries are often extremely unreasonable and self-righteous. You may be judged by someone who thinks shooting at you is no worse than you making dirty gestures at him.
On the road, impatience kills. It can get you shot or cause a horrific accident. If you leave for your destination on time, as a mature adult should, you will be less irritable when you are delayed. Get used to arriving at least 10 minutes early, and when you arrive, do something useful with your time while you wait. Read the Bible. Study a language.
I get annoyed with people, but you have to balance the magnitude of their trivial transgressions with that of the consequences of being a hothead.