Leaves are a constant source of headache for roofers and a constant source of problem for all roofing types; especially for tiled roofs. Tile roofing seems to be the worst affected due to the access leaves have to valleys and gutters.
Have a look at the pictures below, this is a great example of a flat tiled roof having problems with leaves blowing up under the tiles.
The problem arises because once the rain has come and the leaves are blocking the gutters the water then has nowhere to go. The water builds up in the gutters and spills over into eave lines. The leaves turn into a thick mulch which also builds up causing dams and starts forcing the water into the roof cavity thus causing not only external damage like rotting gutters and down pipes and in some cases blocking drainage, but internal damage as well as shown in the last picture above.
This is a reminder how important it is to have checks and maintenance done on your roof regularly.
but also extensive damage can occur to the inside of your property. 
Check out this picture, this could have all been avoided by paying a small cost for a roof check, however, this Sydney couple have left it until the ceiling of their house has fallen through and are now looking at a huge cost in house renovations. 
Though there are many different types of roof, maintenance approaches are generally the same for most of them. But still, there are some instances that extensive maintenance task must be applied to specific roofs. The usual thing done when inspecting a roof involves checking the cladding, flashing, gutters, chimneys and all the roofing materials.
In rainy places in Australia, like Saint Ives, moss and algae may appear on the roof and these must be cleaned up to keep it clean. Also take heed about other materials on your roof like antennas and wires. Make sure that they are installed properly and that they have strong foundation. If there are some branches of trees near your house that hang directly on your roof, you might want to trim them too. Painting the roof, although may be costly, must be done every few years as well. Roofing paint and other roof coatings give protection to the roof’s surface. If there are missing tiles, don’t hesitate to buy some pieces for replacement. Although roof maintenance means you will have to spend some cash, it must be done for your own safety. Remember, prevention is better than cure.