Appearance Looks are important. It's the first thing a buyer will notice. Thoroughly clean your car inside and out. Give it a wax and vacuum, clean the ashtrays, even the trunk. Consider cleaning the engine with a degreaser.
Condition Do a general maintenance check.
Replace oil and all other fluids. Check tire pressure. Keep records of what you've done. In a folder, gather all maintenance records, the owner's manual, registration and title. Pricing Check Kelley Blue Book prices.