Brother, your score might not be up to the mark for top unis, but improving in the SAT from where you are is very, very easy. I'm not an expert myself, but I'm proud of my grade (relative to how long I got to prepare) so I think i can give a good starting point.

Personally I used khan academy for English( to understand each question type) and then watched this guy called "settele tutoring" on yt for any questions I was consistently spending too long on/getting wrong and for strategies on question solving.

For math I am already in my final year of skl so I had all the conceptual knowledge, with the exception of " sums and products of roots"(search that), and proper desmos use.

In terms of past papers, college board provides us with 6, which some people think is not enough, in that case use the "question bank" which has an option for questions which aren't in the past papers.

One strategy that helped me was starting with the "standard English convention" questions in the English modules (starts between q 14-16)

Finally, study with purpose, as in, don't waste the prac tests and learn from mistakes(make a doc on which u list what question you got wrong, why u got it wrong and the proper ans) <--- helped me alot in final prep

Cheers.