How can I troubleshoot the cooling system of my Audi A2?

I've noticed that the temperature gauge on my car is running high and I suspect there might be an issue with the cooling system. What steps should I take to troubleshoot and address this issue?

First, check the level of coolant in your car's reservoir. If it's low, top it off with a 50/50 mix of antifreeze and water. Keep an eye on the level and top off as needed. If it continues to drop, there may be a leak in the system.