Just like driving in real life, there are rules on the road that you have to follow:
To keep yourself from breaking the speeding rule above, one great thing to do is use the "cruise control" feature. Get your truck up to a speed close to the limit (I usually give myself 5 points variance, so if the speeding limit is 65, I'll get up to 60), then press the "C" button to go into cruise control. The game will keep your truck running for you (without you having to hold down the up button) at that same speed until you break. This is great for those long stretches of highway or long-haul drives; one less button to hold down, and you can focus more on switching lanes, if necessary.
Parking can be a bit hard for newbies, especially if you have a big trailer hooked to your truck. When you park when doing a delivery, you'll have three options: Skilled Parking, in which you'll have to back up into the space, Safe Parking in which you can drive straight into the space, and the third, in which you skip parking altogether. While I don't recommend skipping the parking (as you won't be granted any XP points), I do recommend doing the Safe option, at least when you're first starting. You still get XP points for parking and it's heaps easier than trying to back up your trailer. Just take it slow and steady and as soon as you get the notification to lower your legs, hit the T button. Most of the time, you don't even have to get the trailer completely straight.
You've probably noticed the sleep and gas icons on your navigation menu, but when you're doing quick jobs, you don't really need to worry about either one. Quick jobs are designed to be done in a short amount of time, so you should have enough rest and gas to complete them without stopping, unless you've gotten lost or had an accident on the way.
You can check how much time you have before needing to sleep by checking in your navigation menu. Press F6 and look at the "next rest stop in..." to find out how much time you have remaining until you need to sleep. Typically, you have 13 hours at the start of each job (if doing a Quick Job). When you've got your own truck and are doing your own jobs, make sure you do sleep either during your job, or between jobs. To sleep, look for the bed icon on the map (usually situated in gas stations, sometimes hotels, parking lots, etc.) drive into the parking space, press E to turn off your engine and then press Enter to sleep.
You'll gain experience points for completing jobs on time or early, for having your truck and trailer intact, and parking. As you gain XP, you'll level up, and also gain points which can be used to unlock special skills, which further allow you to make more money per job and gain more XP. There are six skills you can unlock in the game:
Check out your GPS while driving- if you're in an area you've never been before, you'll see all the roads are grey, but as you drive down them ("discover" them), they'll turn yellow. You can see the same roads on the menu map. This is a great tip for completionists who want to reach 100% coverage in the game!
Much like driving in real life, it pays to be aware of your surroundings in the game. Some of the highway exits (particularly in Arizona) are a bit confusing so be sure to check your map for your turns in advance. Also beware for things on the road like sudden traffic, accidents, road work, and road closures. All of these random events can impact your journey as well. Don't worry about tumbleweeds, though. Unlike real life, you can run over them without messing up your tires!
If you miss your freeway exit or get lost somehow, don't fear—the GPS will automatically redirect you and find you an alternate route. Also, If you get in a bad accident or can't get "unstuck" from a ditch, call assistance services. It'll cost a fee and take some time out of your job, but they will drive you to a nearby town and you can get your truck fixed, or just continue on with your journey. I don't recommend doing this during quick jobs, though, unless absolutely necessary.
This is more for when you have your own truck and can "free drive", but the GPS isn't just used for getting from one job to another. You can plot pretty much anything on the game's map by dropping pins. Want to drive from the dealership in LA to a rest stop in Vegas? Drop the pins in the menu map and let your GPS show you the way. This is also great to do when you're trying to get to towns you haven't discovered yet.