There is no definitive answer to this question, as it depends on personal preference and the specific design of the hoodie. However, as a general guideline, designs should be placed around 2-4 inches below the hoodie's collar, so that they are visible when the hood is up. Keep in mind that the placement of the design will also be affected by the size of the design itself. If you have any further questions or would like more specific advice, feel free to reach out to a design professional or tailor.