Best action to take when filling outboard portable tank?

When filling an outboard portable tank, ensure the tank is secure and on a flat surface to prevent spills. Use a funnel or spout to minimize the risk of overfilling and to avoid fuel splashes. Always fill the tank outdoors in a well-ventilated area and avoid static electricity by grounding the tank. Lastly, check for any leaks or damage before and after filling to ensure safety.