Using your Spyder Signature Halogen Model Projector Headlights is straightforward. First, refer to the included installation guide to install them on your 2015 - 2021 Subaru WRX or STI. Make sure to follow all the steps carefully to ensure a proper fit. Once installed, you can adjust the headlights using the headlight adjustment guide to get the best lighting angle. Remember, this is a halogen model, so it's not compatible with the factory LED model. Also, don't add HID/LED bulbs as it will void the warranty. For maintenance, regularly check the lights for any dirt or debris. You can clean them with a soft, damp cloth. If you notice any issues with the lights, like flickering or reduced brightness, it might be a good idea to check the connections or contact customer support.