Prepare for new management. As soon as you make the decision to sell, begin doing what you can to help the business run "on its own." The business should not, especially now, be just you!
Accept the financing facts. You'll likely be financing the sale of your business, since banks are traditionally unenthusiastic about loans for the purchase of most businesses.
Make sure your own financials are accurate, detailed, and up-to-date. Get professional help, if necessary, to present yourself well "on paper." Remember - this means seeing yourself in the same light as a prospective buyer, so rethink all those "perks" and hidden assets.
Spruce up and pare down. Sell unused equipment and inventory. Nobody will want to pay for it - but they might worry it will get tacked on if they see it lying around. This is a good time to see what else needs a bit of spit and polish to make the best possible impression.
Establish a realistic price for your business.
Keep your selling plans to yourself, at least at the outset. Employees might react poorly to your "news," and you need their stability more than ever at this crucial time.