Read your work out loud, which will often help you catch grammatical errors. You may miss mistakes if you are only reading to yourself. It's easier to hear errors. If you are unsure about your grammar, use a grammar reference book.
Look for the most common errors in grammar. According to YourDictionary.com, errors that involve run-on sentences, incorrect uses of apostrophes, subject/verb agreement and misplaced modifiers are some of the most common mistakes made in writing. Look for these errors, concentrating on one at a time. For example, first look for run-on sentences, checking your work for only these errors. You will have to skim your work several times, but in the end, you will have fewer errors if any at all.
Read your work in reverse to check for spelling errors. Start from the end of your paper, reading each word separately to catch spelling errors that you may have overlooked. Reading papers from the end to the beginning helps you concentrate on individual words, which will help you to spot spelling errors quickly. When we read papers in context, it's easier to read the word as it should be read instead of reading it as it is actually written. Check a list of commonly misspelled words and skim your paper for these misspellings.
Check your paper for word choice errors. There are words that are spelled correctly but used incorrectly in your writing. For example, the word "their" is different from "there" or "they're." Word use errors may not be caught by spell checkers because the words are spelled correctly. Make a list of your own words and pay special attention to them when they are used in your papers.