The scanner you use has to be one with built in negative scanning ability. Usually, a scanner designed for paper documents wont have this feature, but some do. A good scanner that is suitable for scanning negatives will produce excellent quality scans quickly, and there are different models to choose from that can allow you to scan numerous negatives and slides at once.

Scanning Negatives: DPI and Resolution
To begin, since the image on a negative is so small, you will want to keep a high resolution so that you can enlarge the picture and still maintain good picture quality. A good rule of thumb is that for every doubling in size for the picture, maintain that same increase for your resolution. For example, to get a 4X6in print from a 4X6in scan, the recommended dpi setting is 300. To get an 8X11 from that same scan, double the dpi to 600, and so on.

Scanning Negatives: Files and Output Type
There are several different file formats for images that computers use. These are TIFF, JPEG, and BMP files, just to name a few. The best files for scanning negatives are TIFF files. TIFFs can be edited and saved easily, and without compression loss. However, TIFFs can be large files that take up much memory. Besides choosing a file format, Output Type is another variable to consider when scanning. The default output type is usually Millions of Colors which is the best for photos with lots of color. Grayscale is for black and white pictures. It is recommended, though, that you maintain the default setting for color output, because this maintains the highest picture quality, and photo enhancement software can easily take the color photo and put it in black and white for you.

A word of caution about storage space: Many people have found that file sizes can mount quickly with scanning, saving, and editing photos. Pay special attention to file sizes and how much space is available on a CD or disk that you are saving the pictures to. Try to see about how much space a picture file uses, multiply that by the number of files you are saving, and make sure you dont run out of space in the middle of creating your masterpieces!
Keeping these tips and other important points in mind will help you decipher the puzzle of scanning negatives. These tips will get you started on your way to turning your tiny negatives into meaningful photographs that you will treasure for years to come.