The most common sign is water damage. If you notice any water stains or damp patches in your ceiling, then this could suggest that there is a tear in the roofing material or compromised sealant around one of your roof fixtures, such as a vent pipe, chimney stack, etc., allowing moisture to penetrate through.
If you find shingle granules (small gravel-like particles) in your guttering or downpipe, it could indicate wear and tear on the surface layers of your shingle material. Other physical damage caused by hailstorms, ice damming resulting from intense cold periods leading to snow build-up and melting, etc., can all cause significant wear and tear both visible from the ground and internally within attic spaces where insulation can become wet, leading to further issues overtime if left unattended too long!
Physically inspecting for damage yourself (which must be done carefully due to safety concerns relating to heights) is important also to assess any pest activity potentially occurring around flashing elements, such as squirrel/bird nests, which might require relocation before beginning repair works – so get professional opinion before taking action!