Don't sand down the brake pad, just rough it up. 3-4 strokes is all it takes.

What kind of brakes are these? Some brakes allow you to adjust the angle of the pad, others you pretty much just have to bend the brake. Depending on the type of brake you have, everything you ever wanted to know will be in one of the last three articles at the bottom of this page: http://www.parktool.com/repair/byreg...mageField2.y=9

The point of the rubber band is to show you how much more space there should be between the back of the brake and the rim and the front of the brake and the rim.