Affiliate Marketing Secrets

I just received my SAT score back. I was not prepared and I completely ignored the subtracting points rule and if I ran out of time I would just fill in random answers. I just enrolled in a local SAT course affiliated with the Princeton Review, which would hopefully help me improve my score overall.
I’m gonna be a freshman in high school this year so i have roughly 4 years ahead of me to prepare. My GPA is a 4.0 at a 7-12 prestigious public magnet school that is ranked 3rd in the nation and 1st in my state.
My total SAT score is a 1480 (i know its terrible! I hope I can improve!) :
Reading- 540
Math- 490 (I could understand this score because I’ve only just finished Algebra 1 and beginning Geometry independent study)
Writing- 450 (do you recommend purchasing a grammar book?)
Any tips greatly appreciated! Thanks!