The Rule of Thirds is a compositional tool that dates back to the Renaissance and even before. It is used primarily for landscape painting but is a very useful tool for still life, figures and even portraits. The basic idea is that the strongest areas of a rectangular painting lie where the red lines intersect. You can use the The Rule of Thirds to place your focal point or to create the weighted areas of the composition. Just remember, the one place you DON’T want to place your focal point is in the center square ( unless you intentionally want a boring composition or you are sophisticated enough to know how to counterbalance that space!). If you are a more advanced painter and want a challenge, try pushing the hots spots slightly away from the intersections while still maintaining your painting's balance.