Keep your speed down, check your mirrors every few seconds, 2 hands on the wheel at all time with thumbs on top, keep a good following distance, try to shift smoothly although that's not always easy, let the brakes slow the vehicle down not by shifting.when at a red light the vehicle goes in neutral and put on hand brake(hands back on the wheel while also checking mirrors). when car in front of you moves count to 3 before you move.obey all traffic signs. just remember-you're not driving a sports car.
If it's an older car remember that first gear is wholly unsynchronized and will grind unless you are at a full stop. If you have a habit of resting your hand on the shifter, break that habit now by keeping both hands on the wheel. Make sure you are O.K. with using a clutch, the main thing that causes you to fail is an unsafe act where the supervisor has to take over. Stalling and/or lurching and jumping repeatedly into an intersection is usually gonna meet that criteria. Don't be too easy on the throttle they are slow and it takes some effort to get up to speed even though they are so noisy most package cars sound like they're doing 50mph when you are doing 25- WHICH MIGHT BE 15 below the speed limit! The brakes are just the opposite- they are super touchy because they are designed to stop you when you have 5-10 thousand pounds of parcels in them so be very gentle- they can be super touchy- when stopping in an empty car like the safety cars, or you will cause the vehicle and everyone in it to pitch forward with just a moderate push on the brakes. Remember to turn left lane to left, right lane to right, ALWAYS, and don't "round off" your turns. Rounding off your turns puts you into the opposing lane of traffic and is never safe. Stop well before intersections and crosswalks, you can even leave a car length space between them and your vehicle if you wish, just as you do when stopped behind another vehicle. If you can't see the rear wheels of the car ahead you are too close. As far as checking to the rear don't check your left mirror followed by your right mirror- that takes your eyes off the front of the car for too long. Check one mirror, eyes back to the front, then check the other mirror and return you eyes back to the front. Take the 15 second eye lead time to heart and practice it every day in your own car. If you use it you can anticipate signal lights and people turning in your lane way before you get there resulting in you stopping MUCH less often, since you can slow for lights you are going to miss and then catch them going green as you arrive, and being much smoother and not being surprised by other drivers so much. Relax, and if you feel you are having trouble centering the package car in a narrow lane simply raise your eyes and you can feel where you are. It works amazingly well. All truck drivers use that one, by the way, just never lower your eyes and stare at the lane markers, that will only make it worse. Raising your eyes will also keep you from swinging left on right turns which is also caused by low aim steering drivers. If you go through a turn RAISE your eyes and see the whole turn, and then it's easy to stay in the center of the lane all the way through. I guarantee you'll pass if you genuinely pratice this stuff and follow anything that you're not presently doing. Good luck.
Disneyworld and paganpink gave excellant advice. Follow their tips, and you should do well. Its natural to be nervous, just try to relax and you will do okay. I learned to work a cluch driving a "three speed on the column", nothing to it once you get used to it, in fact it is fun. Good Luck, let us know how you do.