Before you begin waxing, you'll need to clean the base of the board and repair any dings that you may have. It is advisable to make some of the smaller dings wider (see below) before you add the P-Tex. If you don't do this, the P-Tex will just pop straight out as there won't be enough surface area for it to cling to.
Widen any small dings: before you fill any dings/dents with P-Tex, check them against a Dremmel-type drill bit (like the one in the picture). If the ding is smaller than the bit, use the drill to make it wider. Remember, you're only trying to make the ding a little wider (as wide as the drill bit) and NO DEEPER. Be very delicate.