SC

That's, very subjective. It would be great if you can disclose how did you prepare for your SC and what is the source of your 60% accuracy.

I shall share my story and see whether it helps you !!!
I gave my first GMAT in 2010, scored high in Quant but performed miserably in verbal. I still remember I sweated during the exam while attempting verbal. Though I had then joined a renowned coaching institute in Delhi, failed to improve my verbal. Main reasons - Rule-based approach for SC and not giving enough time to rehearse RC and CR.

In 2021, I decided to redo MBA, and hence for GMAT I decided to not join any coaching institute rather prepare on my own. This time for SC I started with the very basics of grammar. For that, I just used English grammar tutorials on youtube. Youtube is filled with amazing English teachers. Just prepare a list of topics covered in GMAT, find the teachers that suit you the best, and go through their videos. I could see a significant improvement in my SC and all for free. But this approach takes time. As a matter of fact, my accuracy in the SC-1000 series has crossed 80%. The only risk is it is an unstructured approach. You should not go so deep in a grammar-based approach as to cross the exam relevancy. For that, I'd suggest a book - "sentence correction, nirvana".

Besides, If your native language is Hindi, I have compiled a list of youtube grammar tutorials I used for my preparation, can share it with you. It would be great if you can specify the topics that hurt you most, shall share the relevant links.

For RC, I'd strongly suggest reading the entire passage completely. It's better to first master the SC, followed by CR, and finally the RC. For RC, I started reading the Washintonpost newspaper online (for a month), and that in my opinion helped me gain confidence and improve my reading speed.