Now you’re ready for some self-editing.  Read over your piece out loud and ask "Does it sound right? And does it make sense."  Again you ask?  Didn't I just do that with revision.  Yes but it is important that you do it a final time to put the final polish on your writing.  

Conventions

Now's the time to get really concerned about conventions.  (Spelling and grammar)  If you need a little help don't be afraid to use your grammar and spell check tools on your word processor.  Then after you edit it ask a friend to edit it for you.  Because after all that work there will be things you miss.

Don't be surprised if an edit turns into another revision.  That is the nature of writing after all.

Need some practice editing.  Go to https://www.studyladder.com/games/activity/editing-text-in-sentences-22743 to practice.