We tend to ignore the roof until it begins to leak. Leaks are expensive and can cause extensive damage. Check your roof for possible damage every spring and fall and after heavy winds, hail, or an ice storm.
Go up into the attic on a rainy day and look for water drips or water stains. If you locate a water drop, trace it to its source. Look carefully to be sure you cannot see daylight anywhere through your roof.
When you are sure the roof is dry, climb up on it wearing rubber-soled shoes and check for missing shingles, loose, cracked or curled shingles, and "bald spots" on the shingles. Remember the sun does as much damage as wind, so look closely at the sunny slopes.