When setting up your car, put low tire pressure in the right side tires. This will give the car more bite through the corners.
Easy money
In Career mode, start at the pro stock cars and hire a cheap driver. Race him for a few races, then fire him and get the best driver available. When you are about to start the race series do not go over to the left to select the car. Stay there and select it. You will be asked you if you want to watch. Answer "No". You will then go to the race menu with the "Practice Heats", etc. options. Go through all that and you should finish first. Do this until you can afford a good sprint car. When you get the sprint car, do the same thing. When you get to the championship you will have a lot of money. Do this a few times so that you can buy the best car. You will be able to win if you can handle the car.