First I would clean the concrete surface real good. Use a recommended cleaner from the paint store or a 50/50 mixture of vinegar and water. Don't skip this step, any contaminants left on the surface and the primer and paint are most likely to peel.
Next seal the concrete with a primer/sealer. The paint store can recommended one. As far as a paint, I highly recommend Grand Distinctions by Pittsburgh paints. It's covers the best and blends well so when dry you don't see lap marks.