Final answer:
For a capillary stick, the puncture is usually made on the external skin surfaces, often on the fingertips, using small glass tubes to collect blood by capillary action.
Step-by-step explanation:
When performing a capillary stick, it is most important to puncture the external skin surfaces. Specifically, common sites for capillary blood sampling include the fingertips and the heels in infants. During this procedure, small diameter glass tubes are used to collect blood by capillary action.
This method is often used for medical analysis, such as measuring blood glucose levels or other blood tests that require only a small amount of blood.