Maximizing Your Superscore
Most schools will allow you to send your SAT Superscore. This means that they will only see your best Math score and your best Reading & Writing score, across all the times you take the test. Let's use this to our advantage! You don't necessarily have to nail the test in one sitting, you just need to get the best superscore you can, because that's what schools will see.
Check The Testing Requirements Of Your Schools
Ideally, you'll have some idea of what schools you want to apply to before you take the SAT. If not, don't stress out! But if you do, then look into what their testing requirements are. In particular, do they require a standardized test score, and do they accept superscores? The vast majority of colleges do accept superscores, but if your #1 school happens to be one of the ones that don't, that's something you want to know. Read the advice on this page either way, but take it with a grain of salt if you're applying to any schools that don't accept superscoring. At the end of the page we discuss how to approach it if some of your schools don't accept superscoring, of if you don't know yet.
Taking The Test Costs Money
I can't skip over this - you do have to pay a substantial amount for each time you take the test. This of course will be factored into many families' plans according to their financial situation. The rest of the advice on this page gives advice as if cost is not an issue, but I recognize that is a very privileged assumption. Please find the right balance for your family.
Take Your First Test Early
If you're absolutely positive that the schools you're appling to all take superscores, then the earlier the better (like maybe December or March of Junior year). Even if you bomb, it won't hurt you if you end up doing better on one of your next attempts. If you're not sure, or if that timing doesn't work for you, then take it early enough that you have time for at least 2 more attempts afterwards.
There are a couple reasons you want to take it early. One is that it can help with test anxiety. Know that your performance on this one test isn't crucial, because you can always take it again. Another reason is just that statistically, if you take the test more times, you're more likely to end up with a better superscore.
After You Take The Test
When you get your score back, identify which section you think you have the best chance of improving on. If you were scoring 700s in reading & writing on your practice tests but you got a 620 on the test, then you can probably improve your reading & writing score next time. Or maybe you feel like you've started plateauing on improving your ability in reading & writing, but you can still do a lot better in math if you memorize some of the formulas better. Whatever your reasoning, try to determine which section you think you have the best chance of improving when you take it again.
Once you've decided, make this section your primary focus as you prepare for the next test. Since your superscore allows you to combine your best from each section, you don't have to do well on both sections on any one test - you just have to do well on one section to improve your superscore. So let's use that to our advantage and really try to boost our score on one section.
But don't stop working on the other section altogether! We don't want to lose the skills we've gained, and you might want to focus back on that section on the following test. You also never know what's going to happen - some students will think they've maxed what they are capable of on Reading & Writing but think they can improve their math score, then end up surprising themselves and doing better on Reading & Writing.
When You Take Your Second (or more) Test
One of the biggest barriers to success for a lot of students is test-day anxiety. Remind yourself that you already have a score that will get you into a lot of schools. You have nothing to lose, only to gain! Don't stress about this test - it's a bonus if you end up doing well, but it doesn't hurt you if you don't.
If Some Of Your Schools Don't Accept Superscoring
Still take it early, but not too early
If you are applying to schools that don't take superscoring, then you'll want to make sure that you have put in some solid preparation before your first crack at the test. I still recommend taking it on the earlier side if you can - don't wait until you think you have 100% maximized your preparation. It's still important to give yourself the option of taking it one or two more times if you don't do as well as you hoped for. Take it again if you think you'll do better
Once you have taken the test at least once, you should only take it again if you think you have a reasonable chance of doing better. If your first test score was well below what you had been getting on practice tests, then it's probably a good idea to take it again. Or if you have continued with your practice, and now you're doing better on practice tests than your actual score, it's worth taking again. But if you've been getting around 1100 on your practice tests, but got a 1200 on the SAT, then I'd probably stick with the score you have. Don't lose focus on one section
If you are applying to schools that don't take superscoring, then don't lean too heavily into the earlier advice about focusing on one section for subsequent tests. Your school will see both sections from every test you take, so you want to make sure that you don't let one of your sections drop significantly on your next test, or they will wonder if the first one was a fluke. It might still make sense to put a little more focus on the section where you think you can improve more, but make sure that you keep your sharpness on the other section at least where it was at when you took your previous test.