Watch the trim first
Soft trim, open gaps, loose wrap, and water stains can tell you a lot about what is happening behind the siding.
Look for movement
Panels that are loose, bowed, cracked, or pulling away from the wall should be checked before more water gets in.
Do not wait on water problems
If water is getting behind the siding, the project can grow quickly. It is better to inspect the area and decide whether repair or replacement makes more sense.