Contact a book editor by visiting her website. Many book editors, whether employed by a publishing house or freelance, have personal websites where you may contact them. Research any editor you find to make sure he has credentials and experience in your genre. It's a good idea to find references before deciding on an editor and don't forget to leave your name and contact information.
Contact an editor via an online self-publishing service like Lulu. If you decide to go the self-publishing route, you still need to have your manuscript edited by a professional. Lulu offers an editing service for a fee that's separate from any package the company offers.
Find a book editor via the publishing house she works for. Most books list the name of the person who edited the book on the dust jacket or within the credits pages. Simply visit the website of the publishing house and send an email requesting she contact you. Make sure you clearly state the reason for contact, and leave your contact information. It's more likely you will receive a response from a smaller house than a large publishing house. If you wish to submit your manuscript for publication, make sure the publishing house accepts unsolicited manuscripts, or you will not hear back at all; keep that in mind when contacting editors. A good resource to find editors' contact information is the The Writer's Market, either online or the printed version found in bookstores or the library.
Hire a book editor using an online freelance site like Elance. This great resource for freelance book writers allows you to search through credentials and resumes of countless editors. Research the editor of your choice using feedback, past jobs and portfolios before awarding your project. You may also invite preferred contractors to bid on your project and set your budget as well.
Find a book editor through a website like the Editorial Freelance Association, which provides contact links to several countries' editor union and information websites. Many countries have unions for both writers and editors and allow for you to contact any editor you have interest in through the union's website. These union sites have great information for curious writers and would-be editors alike, so it's a good idea to browse the information.