I have a couple of tips
First of all, just so you know, it really is possible to ace the SAT (or get pretty close) if you fully commit yourself to putting the work in.
Second, practice is key. Taking as many practice tests as you can (there are 10 or so on Khan Academy) really helps get you used to the kinds of questions the test asks. Pattern recognition is especially important for the reading and writing sections because the SAT uses logic there that is sometimes unfamiliar, and once you get used to it you'll understand the test better. Practicing your weaker sections (and your weaker topics) is really important because focusing there is where you can see the biggest improvement in your test score.
Third, when grading your tests, LEARN FROM YOUR MISTAKES. This is probably the most important. Say you take five practice tests, and on each of them you learn from only half of the questions you get wrong, you're going to see a huge improvement in your score already. Make the mistake on the practice test so you don't make it on the actual test.
Also, sometimes you gotta remember that it's just a test, so don't let yourself get too stressed about it.
You got this!