Besides Spell check, you can use the Grammar check. Just click on the Review tab, and then Spelling and Grammar.
Grammar check can look for capitalization, fragments and run-ons, improper possessives and plurals, incorrect punctuation, subject-verb agreement, passive voice and a lot more. You can pick what grammar check will look for:
In Word, click on File>Options (lower left)>Proofing>When Correcting Spelling and Grammar in Word>Writing Style>Settings.
You can also check for double spacing after a sentence. You can use the grammar checker on word to show places where you made it 2 spaces. Click on File>Options (lower left)>Proofing>When Correcting Spelling and Grammar in Word>Writing Style>Settings>Require:Spaces Required between Sentences = 1. Then, when you are back in the document, click on Review>Spelling& Grammar.
Possibly better directions are here: