There are many things that you can do to prolong the life of your roof, like don't plant trees too close to the house. Cut the branches of mature trees that touch the roof or hang over it. Moss growing on roof traps moisture and rots the shingles. Remove it with a solution of equal parts chlorine bleach and water. Don't do it yourself unless you are sure you'll be safe climbing up on the roof. Check the roof after a storm to be sure that shingles were not blown off. Have missing shingles replaced. Keep the gutters clean, twice a year or more.