Final answer:
The comedone extractor should be inserted into the skin at a 35-degree angle or parallel to the skin for effective extraction without causing damage.
Step-by-step explanation:
The comedone extractor should be inserted into the skin at a 35-degree angle or parallel to the skin. This angle allows for effective extraction of comedones (blackheads and whiteheads) without causing damage to the surrounding skin. Inserting the comedone extractor at a 90-degree angle perpendicular to the skin may cause unnecessary trauma. Inserting it at a 180-degree angle opposite to the skin or at a 45-degree angle may not be as effective in removing the comedones.