Just because a business is being sold, it doesn't mean it's time to let it run down. To maximise price and attract buyers, this is a time for restocking, cleaning and generally improving the presentation of the business.
Prospective purchasers will be interested in the income earning ability of the business. Before a business is put up for sale, you should try to increase the income by increasing trading hours, expanding the sales team, or by reducing expenses.
You can use something as simple as a fresh coat of paint to make a positive impression on a buyer. It helps your business to stand out from others around it. Make sure you fix up any aspect of the property which can make a bad impression on potential buyers before the business is put on the market; improve any surrounding gardens, have the windows cleaned, and fix any broken signage (the name of the business, the signs in the car park).
As part of their due diligence, prospective purchasers will obviously look beyond the surface, but first impressions are very powerful. Selling a business is a marketing exercise so your negotiations with potential buyers should highlight all the positive features of the business.
You should also consider the value of uniforms, even something as simple as a branded windcheater.
Deal with anything that could be a liability. For example, address and settle any outstanding warranty claims, employee claims or tax matters. If the business or someone associated with the business is facing legal action, you should disclose all relevant facts and be honest. The threat of being sued for fraudulent representation overrides any small advantage that may be gained by misrepresenting the true position of the business.