Editing your piece of writing is not about making sure the grammar or spelling is correct (save that for when you proofead the draft that for you is final); it's about making sure that the content is at its full potential.
In your first big edit of a piece of work, you want to make sure that you know -- and are conveying -- the main point, as in why you're writing this piece. It may take a few revisions to fully unearth the main concept. (Remember: The secret to good writing is revision!)
To help yourself with the big things, consider some of these questions as you go over your piece. It's always easier to write more than you need and cut it later than it is to scramble and add more at the last minute. (Hint: On your first big edits do NOT worry about the little stuff; read it through, then ask the questions.)
- What is the main point of your piece? Do you think you get it across? Does it waver, go on tangents? Do you have an underlying point? Is that clear?
- What are the parts that stand out -- emotionally? Do they ring true? Is this something you have experienced? Can you add to it? Or do you need to do more research?
- Do you have enough specific detail? Sensory detail so that it comes alive for the reader?
- Are there parts where you drifted? Be honest; are parts boring? Or confusing? Cut or fix -- add detail or explain it better or take out tangential items.
- Can you completely relate to it? Is it something you have never gone through, and you're just captivated by it? Depending on what you're writing, you can draw on this. You can include a part about your own experiences with or without that topic. This could really make the reader feel like you understand the concept or that you're just as surprised as they are.
- If at any point while you're reading your piece and you come across a point that's a bit confusing, chances are that the reader will be confused too. Have you explained that point well enough? How did you come by this information/event?
- By the end, do you have an understanding of why you wrote the piece, why it's important or powerful or worthwhile?
- Finally, after you've looked closely at each part of your piece, ask yourself whether you like it and try to exclude judgment -- you want to gauge your energy level. If you have found that your energy has waned, why? And is there a part of this writing that you like best that could be expanded?
FINAL HINTS: Editing is the most difficult part of writing. Often our own judgment creeps in and gets in the way. We find ourselves thinking, "I just want to get this done." There is a time for that. But during early edits you are still exploring. You are trying to find the strongest and most interesting story line or focus-- the thing that interests you the most! Remember that if you're interested, your audience will be more apt to be interested; conversely, if you're bored, the readers won't even finish it.