I want to be admitted to a good university, like Stanford or UCLA? Advice?

You are doing better than most students. But read and keep up with current events. When you read, you pick up on structures, vocabulary, and problem solving. (All important skills for SAT and college) Prepare for you sopre year, especially for AP Euro. I suggest for all your future AP Cles: buy a review book and read ahead that too. Practice your writing skills too!