Accuracy in doing sentence corrections

Firstly, I am not a native English speaker and I assume that you aren't one either. What helped me a lot to get a relatively high verbal score was that throughout my life, I have read countless novels in English. My reading many books in English has helped me to get really good at reading, writing and comprehending really fast. When I was studying for the Gmat, the Manhattan Prep Gmat Sentence Correction guide and the practice problems on the Official Guide (you can purchase them both from amazon in e-book format) proved to be most helpful for the SC section. If possible, it would be useful for you to get really accustomed to how the English language "sounds" by reading interesting books in English, talking to native English speakers, and even watching tv in English. Once you know how the English language "sounds", you will see that sometimes you'll be able to correct a sentence without really knowing why it's wrong or right (On the contrary, if you don't know how it sounds you may know the SC rules but won't be able to correct a sentence). By how it "sounds" I refer to how sentences are constructed in English rather than how words sound in English. Also, practice makes perfect! Practicing Critical Reasoning and Reading Comprehension problems will also help you a lot to master the Sentence Correction section since you'll be exercising your reading and comprehension skills which means that, with time and practice, you'll able to read, understand and solve a problem more quickly and accurately. Finally, keep your expectations reasonable; after all, we non-native English speakers are at a true disadvantage in the verbal section, and to many of us, the verbal section proves way harder to master than the quant section.