First impressions count, so give your car a thorough clean inside and out or pay for a professional valet instead. It's also a good idea to remove any personal belongings. This makes the car look newer and well-kept to any potential buyer.
You could touch up chips and scratches professionally before an appointment. Fixing any obvious flaws to the exterior could make a considerable difference, as long as you don't spend too much money. Small windscreen chips, for example, can usually be repaired under your car insurance at no additional cost, and with no effect on your no-claims discount. It also might be worth getting any minor repairs, such as dents, done, as this will help you achieve the best price possible.
You can command a higher sale price the longer the length of MOT on the vehicle. A full-service history is a powerful incentive to buy a car as it signals a responsible owner. If your MOT is due to expire within the next 3 months, it is certainly worth considering putting the vehicle through a test to ensure you can sell for the best possible price. If the MOT finds any mechanical faults with the car, these should be repaired before selling.
Calls cost 3.5p/minute from a BT landline. Other service providers including mobiles may be higher. In addition you will be liable to pay your service provider's access cost.