DEET is typically applied topically to the skin or on clothing to provide protection against insect bites. Here are some guidelines for the application of DEET:

1. Apply to exposed skin: DEET should be applied to exposed areas of the skin that are at risk of insect bites. This includes arms, legs, neck, and face (avoiding eyes and mouth). Use your hands to spread the product evenly over the desired areas.

2. Follow product instructions: Read the label of the DEET-based product you are using and follow the instructions carefully. Pay attention to the recommended concentration for the desired duration of protection.

3. Use sparingly: DEET is effective even when applied in small amounts. Avoid excessive use, especially on children, to minimize the exposure to the active ingredient.

4. Avoid under clothing: It is generally recommended to apply DEET directly to the skin rather than under clothing. This helps ensure proper repellent action and reduces the risk of irritation from prolonged contact.

5. Avoid sensitive areas: Do not apply DEET near the eyes, mouth, or on broken or irritated skin. Take care when applying it to the face, and use your hands to apply it in a targeted manner, avoiding contact with the eyes and lips.

6. Reapplication: The duration of protection provided by DEET varies depending on factors such as concentration, temperature, and sweating. Reapply the product as directed on the label or as needed to maintain the desired level of protection. It is generally recommended to reapply DEET every few hours, especially in hot and humid conditions.

7. Clothing application: DEET can also be applied to clothing for added protection. Spray the repellent on outer layers of clothing, such as shirts, pants, socks, and hats. Avoid spraying directly on the skin under the clothing. Note that DEET may have a greasy feel and can potentially stain certain fabrics, so it's advisable to conduct a patch test on a small inconspicuous area of the clothing first.

Remember, it's important to read and follow the specific instructions provided by the manufacturer of the DEET-based product you are using. If you have any concerns or questions about the application of DEET, consult a healthcare professional or the product manufacturer for guidance.