Start a championship on easy. You need to race twice every track. At the end of championship you will get the "win a race", "win 10 races", "win 20 races" as long as "win a championship" achievements. If you find it difficult to win just pause the game and restart the race. I didn't take the warm up and practice rounds and from schedule i start directly the race. This way the disadvantage is you start last but you save much time and at easy setting you will not have problems getting first. I found out that the most difficult part in every race is to turn correctly without collision at the first turn. After that you probably race alone at the head.