Clean your rims with something like Simple Green. Remove your pads and sand the surfaces, either with sandpaper/file or simply scuff them on concrete (works awesome). Reinstall the pads, ideally with a smidge of toe-in (for front brake pads, the edge of the pad farther away from the fork should be a little bit closer to the rim than the back edges). Check that your cable isn't binding anywhere and pulls freely. Adjust the cable such that you can get the lever in enough that your hand is making good power, but not so far that you can make the lever touch the grip. That should get your brakes dialed.

-Paul