Check for indoor leaks
Take a good look at the walls and ceilings and look out for mould, discolouration or water leaks.
If gutters are not clear of debris and other dust, they will not be able to perform properly and you might risk flooding
Seal windows and doors
Even tiny gaps might let water in so inspect carefully. Old and wooden apertures require the most care.
The roof has a very important role of keeping water out of the house. Make sure it is properly mantained, and be sure to inspect it closely, especially after heavy rain.