My PSAT score... was not what I wanted it to be... any suggestions on how to improve?

Hiiiii!!!! I got my PSAT results back today too...i have a 65 on critical reading, 59 in math and 53 in writing, 177 in total and in the 86th percentile... For me this is good enough since i go to school in Hong Kong and i'm not a native speaker of english but i guess if you want to improve you will have to tackle those grammar stuff and read more challenging books... btw. i HATE grammar so even though i know i'll have to work on it, i don't...