I do SAT tutoring, and when I did the SAT, scored in the 99.8th percentile! Also, I am a friendly panda bear, and I want to give you a few tips if you're struggling!
Step 1 : Get the official SAT study guide. The blue one by CollegeBoard. EVERY SINGLE OTHER SOURCE OF INFORMATION REGARDING HOW THE SAT 1 TESTS YOU IS JUNK! Forget Barron's, Princeton, and everything else.
Step 2 : Maths is the easiest 800/800, fact. You MUST get an 800 in Maths, or very close, if you are aiming at scoring high. Start by doing a few sections in the official study guide. Not scoring as high as you expected you would? RELEARN YOUR MATERIAL. Go over all the material you should know by now on khanacademy.org, and also in the Official Study Guide (lots of helpful tips, and information on what's coming up on the SAT, along with practice tests). After you've done this.. Here's a few things I like to remind my students about - most of the SAT 1 Maths questions are designed to be answered by an average high school student within 1 minute. If it takes you longer, you are either doing the question wrong, do not understand the concept right, or are simply wasting time. Eg, once, a question asked a student to find 4x^2 - the student first found x, then squared it and multiplied the answer by four. This is wrong! When the SAT 1 asks for 4x^2, this means you can find that without having to find x first - think about how you will approach the problem and find the solution before diving into it.
Step 3 : Get a 750+ in writing. Writing seems super duper hard, no? Do the practice for it. ALL OF IT. Using the official guide. Within the official guide, read everything there is to read regarding writing, other than the essay - you should now be scoring well over 80-95% (most of writing is one or two grammar rules - parallelism, concepts like this). For the essay - you must learn to write fast. Content > Quality. This is not very apparent before you do the SAT, but will be after you've done it at least twice. As long as you stick on topic, and make sense and express a sensible opinion, your essay should be as long as possible, as long as it also has a good structure (intro, 3 body paragraphs, conclusion) - practice this at least 5 times before scoring yourself. The writing section was honestly my favorite, because after you realize it's just a few simple rules, you'll start to do really well on it. Check SAT MysteryTutor videos online, those might help.
Step 4 : For Critical Reading, after doing everything in the official guide, watch SAT MysterTutor videos, and read philosophy books while attempting to understand them (Meditation 1 by Descartes is good), and just relax. It's easier than you think. Critical reading is usually the killer for most students who haven't read consistently before doing the SAT 1. Nothing can remedy your lack of understanding of the knowledge - other than building that. Read the most challenging material you can get your hands on - scientific journals, philosophy, even law - all online if you want to, and attempt to summarize the concepts drawn out in the codices, and see if you're really nailing it by retaining everything you've read. Once you're able to do that, you'll get a great score on CR, no sweat.
Step 5 : Relax like a panda. Pandas have never scored under 2200 on the SAT, and neither should you. Chill, eat some bamboo, sleep, sit down. It's just a test, there are some answer choices, you know maths, you know English, you should be able to score well on this test after all that hard work, and you will, there's no such thing as luck - lucking out of a 2200 - if you put the right stuff in, you'll get the elusive 2300+.
Bonus Step : Buy Barron's guide to a 2400. That helped me loads. ^_^
