First, does it make sense?
Check for typos that spell check won’t catch.
Do a sanity check - does it make sense? If I were the client, what would I be thinking as I read this?
Be consistent in how you refer to client-specific items. Even if they don’t have a brand guideline to follow, be consistent in how you refer to their products and processes.
Are your sentences clear and to the point? You don’t get any points for complexity or “fancy” sentences. Get rid of empty phrases.
Did you use simple words, rather than more complex ones? You don’t get any points for trying to sound corporate or smart.
If you know that ESL learners will take the course and/or that it will be translated, avoid American colloquialisms.
Be conversational. Ask yourself, “Would I say this in a real conversation?” If not, get it to a point where you would.
Don’t use passive voice. The person/thing doing the action should be the subject of the sentence.
Stick to one voice. Don’t switch between past, present, and future.
Use present voice, unless it doesn’t make sense. For example: Instead of “learners will” just say “learners”.
Second, does it follow the rules?
Make sure everyone agrees.
Do your nouns and pronouns agree?
Do your subjects and verbs agree? Remember that “they” and “learners” are plural subjects and need plural verbs.
Follow the Chicago Manual of Style unless otherwise specified by the client.
Check especially that you are using commas correctly. Comma mistakes are the errors reviewers fix most often.
Write out numbers from zero to ten as words and numbers above ten as numerals.
Use spell check. There’s no excuse for not using the tools available to you.
Third, does it look good?
Use bullet points correctly.
A list implies there is more than one thing. Always have more than one bullet in a list.
Use a period if a bullet point completes a sentence or is its own sentence.
Make sure each bullet point uses parallel construction. Start each bullet in the same way (verb, adjective, noun, etc.).
Use Word styles.