That's a good question and a 250 points increase is actually really doable! I took the SATs awhile ago, but here are some tips I would recommend:
- Practice makes perfect - For me, I knew my weakest subject was Reading. I bought every single SAT practice book I can get my hands on and just did one or two practice sections a day. (My local library had a ton of practice books as well, but I invested in my own so that I can make notes and come back to questions when I needed to). Any question I missed, I would not only review the answer, but I would flag that question to come back to later in the week. I made sure I can correctly answer any of the questions I missed each time I came back to them.
- Vocabulary is important! - Within Reading, I knew I had to work on broadening my vocabulary and the ability to identify context clues. I started reading articles from Time Magazine and New York Times in my free time and also, for each practice test I did and any article that I read, I made a list of any of the vocabulary words that I didn't know and made sure to learn and memorize the definition (coming back to that list frequently to make sure I didn't forget the ones I previously memorized)
- Keep a record - In order to assess progress, I made a list of all the practice tests I did, how many questions I missed in each one and the scores I received. It helped mw continue to track and monitor my improvement and made it easier to come back to and review any questions that I got wrong.
I know everyone's method to studying is different, but I really do think the more context, practice and familiarity you have with the test, the better you'll perform! Doing the above, I was able to increase my Reading section by a significant number of points (scoring a perfect 800) on what was my weakest subject by far when I first started the studying!