A tip I learned from watching TV cooking shows: When making muffins or cakes with fruit such as raisins or blueberries, mix the fruit in with the dry ingredients before adding the liquids. After the fruit is coated with flour, it won't sink to the bottom of the batter. If you're supposed to add the fruit after the batter is mixed, toss it with just enough flour to coat the fruit, then add to the batter.