The common failure points
Hoses go hard and split. Water pumps develop bearing noise or weep from the seal. Thermostats stick shut. Radiators clog or crack at the plastic end tanks. Cooling fans fail, which shows up as overheating in traffic but not at speed. Each has a different cost and a different urgency.
Coolant is not universal
Modern vehicles specify particular coolant chemistries, and mixing types can cause gelling and corrosion. We use what your manufacturer specifies.
If it has already overheated
We check for head gasket damage before assuming a simple repair will hold. Fixing the leak on an engine that has already been cooked, without checking, would just hand you a bigger bill later.