The answer to 'how to maintain skylight' is to regularly inspect, clean, and reseal your skylight to prevent leaks and damage. This includes checking for cracks or gaps in the sealant, cleaning the glass to maintain visibility, and replacing the sealant every 5-10 years depending on the condition.
It's important to be cautious when working on a skylight, as they are located at heights and can be fragile. If you are not comfortable working at heights or performing these maintenance tasks, it's best to hire a professional roofing contractor to handle the work for you.