Keep the gutters clear
More roof problems trace back to blocked gutters than people expect. When gutters fill with leaves and moss, water backs up, spills down the wall and works its way into the structure. Keeping them clear, especially after autumn, is the single most useful thing you can do for a roof.
Watch the moss
A light covering of moss is mostly cosmetic, but a thick layer holds water against the tiles and sheds fragments that block gutters and valleys. If moss is building up, it is worth having it cleared carefully rather than left to thicken.
Look after a storm
High winds are when tiles slip and flashing lifts. After a big storm, take a look from the ground for anything out of place, slipped tiles, debris in the gutters, or pieces of tile on the ground. Spotting damage early means a small repair rather than a leak.
Stay off the roof
The most important point is a safety one. Roofs and ladders cause serious falls every year, and a roof is not a safe place to inspect or clean without the right access and training. Look from the ground, and leave the close work to someone equipped for it.