Rely on resources within your college or university program to find an editor for your thesis or dissertation. Many colleges--like Texas A&M University--maintain a list of appropriately qualified graduate students, faculty or staff who perform freelance editorial services for students writing their theses or dissertations. Visit your university's writing center or the English department offices to find out if your college maintains a similar list.
Use community resources such as Craigslist to find an editor for your thesis. Featuring local community bulletin boards for dozens of cities nationwide, Craigslist not only offers you a centralized forum to post a notice about your need for an experienced editor, but it also lets you review existing posts in the "writing/editorial" section to find an editor. If the editor's location is not important, consider reviewing Craigslist community posts in other cities with a high concentration of academic institutions--you will have a higher likelihood of finding an experienced editor.
Find an editor for your thesis through thesis editing services such as Edit911 or First Editing (links in References). Although using an editing service sometimes means paying higher fees than what you might pay a freelancer, there are many benefits. Editing services pre-screen editors for experience and test for skill level, ensuring quality and experience. Edit911 notes that all of its editors hold Ph.D. degrees. Editing services also are accountable to the Better Business Bureau and similar organizations. Some services--like Edit 911--have edited upward of 10,000 dissertations with a reported fast turnaround, meaning there is a greater likelihood of a professional process, with less concern about follow-up and timely editing.