With reference to unr.edu, these are twenty of the most common surface errors

• Missing comma after introductory phrases

• Vague pronoun references

• Missing comma in a compound sentences

• Wrong words

• Missing comma(s) with a nonessential elements

• Wrong or missing verb endings

• Wrong or missing prepositions

• Comma splices

• Missing or misplaced possessive apostrophes

• Unnecessary shifts in tense

• Unnecessary shifts in pronouns

• Sentence fragments

• Wrong tense or verb forms

• Lack of agreement between subject and verb

• Missing commas in a series

• Lack of agreement between pronouns and antecedents

• Unnecessary comma(s) with a restrictive or essential elements

• Fused sentences

• Sangling or misplaced modifiers

• Its/it's confusion 

Now you as the writer would not be able to tackle all these errors, but me as a writer, editor and proofreader would. Other problems I tackle in your document are readability, negatives, redundancies, plagiarism, incorrect references or errors in references, paraphrasing, readers' disinterest in document and paragraph relatability.

As the writer, you don't notice these things, but that's okay, I'm here to fix it for you without shifting from your writing style. 😃