Shavings should be white or cream colored. Dark shavings represent a decay spot and provide little sugar water. Furthermore, the water tends to be off-flavor. Always use sharp drill bits. Angle the tap hole slightly downward.
Clean wood shavings out of tap holes.
Always be careful not to overtap when seating the spile. A loose spile can be tightened but an over-tapped spile results in a cracked cambium. All of the sugar water leaks out and the tree is damaged. Hold your arms steady while drilling or you may produce an oval hole. Spiles may not seat well in such holes.