Right, surface prep is VERY important. After sanding, wipe down the surface with acetone, do not use solvents such as paint thinner, as they leave oily residue that can interfere with proper adhesion.
Supplied with the keel guard is an adhesion promoter that works in conjunction with the pressure-sensitive 3M adhesive on the keel guard. This adhesion promoter is in an applicator vial, you activate it by breaking the glass ampule, then wetting the applicator tip. Follow the directions closely for this.
Also, if you have a heat gun, that will come in very useful for warming up the keel guard to make it more flexible, and the heat also makes the adhesive kick better.
Use the burnishing tool supplied (looks like a paint scraper made from plastic), and work small areas at a time, making sure to run down in the grooves with the tip of the tool, applying a good bit of pressure... this guarantees full contact adhesion.