Inspect them when the engine is cold. Any sign of wear or deterioration is a danger signal: the sudden loss of coolant from a burst hose can result in rapid overheating and a seized engine.
A worn or damaged hose should be replaced as soon as possible.
Before this can be done, you need to drain the cooling system. Remove the radiator cap and open the radiator drain tap. If there is no tap, disconnect the bottom hose. If the coolant contains antifreeze that you wish to use again, drain it into a clean container; do not drain it on to the road, it is poisonous (See How to flush an engine radiator).
Before fitting a new hose, make sure it is the correct replacement. Some have built-in curves, others have different internal diameters at each end. Old clips should also be replaced preferably with worm-drive ones, which have a larger contact area and make a more effective seal.
Never overtighten any type of clip: it may cut into the rubber.
Once the hose has been replaced, turn off the radiator tap (or reconnect the bottom hose) and slowly refill with a water and antifreeze mixture.
When reusing coolant with antifreeze, strain it through muslin or a plastic tea strainer. Replace the radiator cap and run the engine up to working temperature. Check for leaks, and tighten clips if necessary.
When the engine has cooled, make sure the system is topped up to the correct level. Never remove the pressurised cap while the engine is hot. It will release a jet of scalding liquid.