Check for blisters in the roof. Call a local qualified contractor to patch them. Click here to see how. Keep all gutter free of debris. Make sure that the downspouts are draining properly by water testing them.
Water test any sump drains twice per year.
Once in the spring and once in the fall before winter sets in. If they don't drain properly, call a plumber and get them working properly. Drains will often leak if they are holding water. Trim back any overhanging tree branches. Check all caulking and sealants on flashings and copings.