too dense:
- for baking powder cakes - increase the baking powder somewhat or; separate the egg whites, beat them* and fold them in last or; decrease the amount of sugar
- for genoise - 2 main likely causes are either under-beating the eggs or possibly even overbeating*.
- for either - sift the dry ingredients together 2 or 3 times, don`t just stir them together with a spoon or whisk
- reducing the shortening will make it lighter, but also drier
too dry:
- overbaked is a likely cause; reduce time &/or heat
- too much flour also likely; either sift the flour into the measuring cup, measure it by weight, or simply reduce the amount somewhat
- increasing the sugar or shortening will make a cake more moist, but will also make it heavier
* when beating egg whites, beat them only until they make soft peaks. if youbeat them until they are quite stiff, when they bake the heat will make the air bubbles expand even more and they will "pop" and deflate