Allowing a few drops of insulin to drop from the needle tip ensures there are no air bubbles and nothing is obstructing the flow of insulin.  Once your pen is ready to use, dial the dose you need to administer.  Using a fresh needle, a primed device, and the correct dose dialed on the pen device, you are ready to administer the injection.  Follow your doctor's instructions on pinching the skin and the angle of entry in order to more effectively administer the insulin. Once you have pushed the thumb button completely in, count slowly to ten before withdrawing the needle.  If you are administering a larger dose, your doctor or diabetic healthcare provider may instruct you to count beyond ten to ensure the dose is properly delivered.  Counting to ten or beyond ensures that you get the full dose intended and helps to prevent leakage from the injection site when you withdraw the needle. Insulin pens and cartridges should not be shared. Even with fresh needles, there is still a significant risk of transferring skin cells, disease, or infection from one person to another.

Summary:
Prime the pen device. Administer the insulin. Use your pen only for your own injections.