I usually get 6 wrong in reading and 3 wrong in writing. What should I do to boost my score to a 800? What resources should I use?
Erica Meltzer’s Critical Reader and SAT Grammar Guide (not workbook).
It looks like you are already scoring very high in English, which is great! For the questions you missed, maybe you could go back to review them to figure out why you missed them and focus on those particular areas. Hope that helps! 
Read as many books as possible!
In reading, don’t ask yourself, “Is A correct?” Instead ask yourself, “Why might A be wrong?” You’re more likely to find the flaw that way. If an answer choice is even slightly off, it’s wrong. The correct choice will have support for it in the text.
Remember: If a single part of an answer is wrong, the whole answer is most likely wrong.
Also, even if a question gives you a quotation from a passage, it might help to look at the rest of the passage too.
Don’t spend too much time on vocab, as long as you know the common words that appear on SATs.