Many writers and editors will say the best way to proofread is to read your work aloud. The reason is that by hearing the written words, you will be more likely to catch any errors. If a passage doesn’t sound right to the writer who spent days working on it, then it won’t make sense to the readers who are seeing it for the first time.
Typos are different from frequent errors. Nobody wants to see typos but they can, and do, happen. It’s late at night. You’ve looked at the page so often, you have it memorized. You know what it is supposed to say so your brain convinces you that it really does say that. It isn’t until you see the work in print that you realize your finger slipped. For example, you typed a comma instead of a period, or added an extra letter to a word which created a new word and changed the meaning of the sentence. After all, writers and editors are human.
But when errors exist every few pages, they are no longer typos. Even if there are no misspelled words, it is a good idea to check your work. Did you use the correct verb tense?Is it clear to the reader which character is speaking? Were any words left out of a sentence? Is the punctuation correct?
In addition to grammar, another reason to proofread aloud is for style content. If you’ve written a book that is set in another century, make sure the language style is consistent with the time period. Style consistency isn’t just language, but also customs, clothing, food, furniture, etc.
A third reason to proofread aloud is for description consistency. For example, your novel has a female character with brown hair. Halfway through the book, she is described with red hair. This is a great opportunity to tie up any loose ends in your story. Typos might still appear in the finished product, but they will be very rare.