Do A LOT of prep!!! I’m 800 in Maths too and one tip i learn is that whatever section you’re weak in, be that algebra, probability or statistics try to do a lot of prep on that section. Buy yourselves a SAT Math book - I recommend SAT Math by Barron. U can also search up past SAT Math questions and do them. Try to do at least 5+ practice test per day. @smiteme