Self-editing is a skill one can build, as with any part of the writing process. It may not come naturally at first, especially for students who have not written a research document of this length before, but remembering some simple steps will help the habit grow:

• Begin with the idea of Reading to Write. Actively reading will help you prepare for writing. 
• Do not try to write a perfect first draft, and always expect feedback and revisions.
• Wait until the content and ideas are solid before polishing and refining.
• Make revision the most important stage in the process.
  • Block off at least as much time for revision as for initial drafting.
  • Take time away from the document before rereading (at least a day is ideal). This allows you as the writer to see the document with fresh eyes. Taking a step back can provide a fresh (and possibly more constructive) perspective.
  • Plan still more time at the end to proofread and polish what was revised. 
• Be self-aware of strengths and weaknesses as a writer.
• Start a writing group and/or offer to trade drafts with colleague to practice critiquing writing.