Don't get rid of your favorite guitar just because it has a few dents and dings. Professionals will often repair a crack or ding for you, but it can cost you. A slight crack or dent isn't impossible to repair yourself. It may take some work and a few tries, but with the right tools you can shine up your guitar and make even a damaged guitar body look new.
Use guitar wax and give the guitar a good rubdown. Find a clean silk cloth and apply the wax generously to the body of the guitar. Carefully but firmly spread it around in a circular motion.
Fill large cracks with wood glue. Use the special tip on the wood glue to insert a very small amount. Tightly bind the glued section of the guitar together (neck or headstock), or just leave it out to dry if it's located in another area.
Fill very small scratches with clear nail polish. Carefully apply it with a small brush. When it dries, it will fill the scratch mark.
Sand around chips to fix the rough edges. These areas will likely need to be repainted anyway, so get a sander and smooth the area down to prepare it for painting.
Go to your local guitar shop and ask for touch-up paint. Bring in your guitar to find a closely matching color. Apply small dabs of paint to problem areas and let dry.
If you can't repair the damage yourself, seek out a professional. Take your guitar to a guitar luthier and have him repair the damage to the body.
With enough wax you can often fill very small dents and buff out small scratches. Use a material, like silk, that won't scratch the finish of the guitar.
Often the paint on the guitar can be fixed in small patches without repainting the entire guitar. Wood glue is great for fixing cracks, but it might not blend well with your paint.
Only sand or alter the body of your guitar if you know exactly what you're doing. These changes can be irreversible.