I have a little mold on one wall in the basement. If I waterproof the basement, will this stop any more mold?

 

You need to kill the mold first. If you do that and then waterproof, it should prevent new growth. To kill it, mix up a bleach and water solution (bleach bottles tell you how much to use) and wash the moldy areas. Be sure you've scraped off any loose paint/concrete that mold may have gotten into. Once you wash the areas, just let it dry and begin the water proofing.

One note, though. I have used Drylock latex-based paint in 2 moldy basements. It hasn't been on the walls long enough for me to know how well it's water-proofing properties work, but as far as coverage of old mold and water stains, I give it mixed reviews. On my own basement (a 75 year old house with some seriously moldy corners) it worked great and covered the old stains very well. But in my mother-in-law's basement (a 30-40 year old house), it wasn't so successful. I've put like 5 coats of paint on the moldy areas and the old stains keep bleeding through. The only advice I've been given is to use the oil-based Drylock instead. Just something to keep in mind if you run into this same problem and you want to hide all the old stains.

 

Mold spores are everywhere in the air. They tend to settle on dark, damp, unventilated surfaces. Sealing basement walls will tend to minimize the transmission of moist vapors but not resolve moisture problems. Warm, moist air in basements can condense on masonry walls, making for a wet surface where mold spores can settle.

Reducing humidity and improving ventilation in basements tends to keep mold/mildew at bay. A dehumidifier will help reduce humidity and fans will improve ventilation.