Join the road every day. Unless you have muscle memory, you need to roll more hours of driving. It may even be trolling around a deserted Parking lot or a leisurely ride along a country road. Your goal is to get used to the car, to automate the acceleration, braking, straight line path of movement, to get used to the machine dimensions.
Get rid of psychological clips and fears. Your lack of confidence causes mistakes and resentment of other road users. Hang on your rear window sign "the student behind the wheel" (exclamation point in yellow square). For other drivers it would be a sign that you do not need to do sharp maneuvers and transitions, zooming in response to your slowness. If at some point you feel that losing control over the situation, activate the alarm and pull over. Take rest, think and take the road.
Learn to predict the actions of the members of the movement. You should always keep under control everything that happens around your car. The car in front you have to count on two forwards. If there's a truck that blocked the view, outrun it or move on. Otherwise there may be a situation when a car going in the front, dramatically rebuilt before the arisen obstacle, and you do not have time.
The most difficult students call work with a manual transmission and rebuild in heavy traffic. Mastering the "mechanics" requires more time, but the driving pleasure you get is also greater. Plus the manual gearbox is more comfortable and safer in the winter. Rebuilding in heavy traffic requires the driver feelings of speed and distance. You have to learn to accelerate to the speed of the flow, hold it and regroup at a safe distance.