Choose a primer before you choose a topcoat. Most basements are merely cement bricks, so get a good cement primer before painting.
Choose a lighter color paint for the walls. This will reflect any and all light which will create a light and airy space. Using darker colors will make a basement look like a dungeon and should be avoided.
Use a semi gloss paint, as much to reflect light as well as resisting moisture. Basements are inherently damp, and if you use a flat paint, the dampness will penetrate the paint surface and possibly cause mold and mildew to form.