Current junior, I took an SAT last year as a sophomore and I scored a 2220.
As everybody mentioned, CR is very hard to raise; practice and a lot of familiarity will help you the most here. Math section is very straightforward (just apply the formulas and don’t make careless mistakes, the content is not very difficult). The writing section score can be improved a lot by studying vocabulary and grammar rules. A major portion of this section is identifying grammatical and punctuation mistakes, so learn your grammar rules and your score will easily go up by 150-200 points. I used www.englishpage.com when I studied, this is a great resource. Just go through each lesson and do the practice, it’s great help for the SAT.
Tutoring may also help in some cases, but I found self-studying to be the most effective method for me. Do a lot of practice tests and see where you stand, work on the things you need to improve on.
Also, figure out how to optimize your score by seeing how many questions you should skip (i.e, if your writing score is below a 680, consider skipping a couple of questions to avoid the penalty)