New paint is usually the most profitable improvement you can make when getting your home ready for sale. So unless your paint is already in like new condition, you probably should paint.
The curb appeal of your home plays a big role in the sales process and you'll never get another chance to make a good first impression. If the exterior of your home obviously needs new paint, potential buyers may decide to skip looking at your home.
A fresh coat of paint on the inside of your home is another improvement that usually pays dividends by making your home more marketable. You'll get more buyers looking, they'll like what they see and you'll have a better chance for a quick offer at a higher price. Try to stick with light, neutral colors. They are widely accepted by most buyers.