Become a Driving Role-Model
In the city
Try to maintain a constant speed at all time. Changing speed from one corner to another, braking and then accelerating over and over again could really annoy the other drivers. The main principle of not getting on one's nerve is to keep as lower profile as possible. Low profile means constant speed, which one must calculate carefully while in traffic. If the traffic is crowded, doing a constant 50 mph doesn't help nobody. Take into consideration the obstacles you're about to face on your regular route (intersections, traffic lights, etc) and adjust your speed accordingly.
Stick to your regular lane when in heavy traffic. You might be hurrying on your way to work, but if you're in heavy traffic, pick a lane and ultimately stick to it. Yes, one lane could go smoother than the other, but you'll probably save only a few minutes in the end. However, the displeasure caused to the other drivers would be useless, as your constant changing the lanes makes the traffic even heavier.
Brake and accelerate smoothly. If you want be one of those guys who think starting from the traffic light with a burnout impresses someone, well... you're not very bright. First of all, you have to have the right car for it, and secondly, there are plenty of situations when you can do this rather than in crowded traffic. The best thing you can do, whether you have to accelerate or brake for a stop of a traffic light, is press the pedal smoothly. This way, you'll avoid giving the guy behind you a heart attack.
If you've made a mistake and the other drivers honk you, don't respond. Nobody can claim they were born perfect drivers. One can make some mistakes while driving, but it's not the end of the world. The simple gesture of raising your hand and admitting you were wrong could save you a lot of honking, swearing and other unnecessary gestures that would ultimately make your day worst.
Don't force the stop signs or the traffic light. No matter if you're in a hurry or are sick and tired of waiting at the stop sign, don't proceed without prior checking. Also, wait until the traffic light goes green and then go. There's no point in forcing the traffic light for only a few seconds to gain. Also, blocking the right lane if your intention is to go straight ahead is also wrong. No matter how long the line is, stay on the right lane and don't block other lanes.
On the highway
If someone is trying to make a pass, just let him. If the person behind you is clearly faster than you, just let him go. Don't be a child and block his way just because you envy the guy or something. If anything, it's stupid. You can always go back to your lane after the car has moved over.
Don't abuse driving on the left lane. There might be some drivers behind you that want to go faster. Don't speed up yourself just to stay ahead of them and risk a speeding ticket yourself. But don't block them either. Just let them go. However, if you find a guy on the left lane driving slower than you but has no place to go – as the right lane is occupied – don't honk them. Just wait until he switches to the right lane and than pass the guy.
Avoid blind spots. We all know the two mirrors (interior & exterior) are not enough for someone to see if a driver is trying to pass you or not. Therefore, avoid entering the blind spot of fellow traffic participants. Also, make sure you checked every possible angle before making a pass on somebody. As always, signal you intention first and then proceed to changing lanes.
Don't tailgate. For me personally, this is one of the most annoying things anyone can do on a highway. Here you have plenty of space and a number of choices to signal your passing, yet you prefer to risk a terrible accident just to make a point. Yes, I know you're faster than me, but I cannot let you go if the right lane is not clear. Tailgating usually makes the first driver more nervous and, if he's also a beginner, likely to make a driving mistake.
Don't abuse flashing your lights to announce your getting over. At night, the best way to signal someone that you're trying to get over is to flash your lights. However, do that only after a few minutes in which you make sure the driver in front of you is clearly not paying attention to the traffic. However, a single flashing light is enough, as excessive signaling usually has the same effect as tailgating: it only produces more nervousness.
Don't use the right lane to get over other drivers. The right lane is used solely for slower drivers. The only thing you can do is cause an accident. Wait until slower cars from the left lane turn right and then accelerate.