The way I ensure that my cake layers will be moist and never dry, is to invert the layer(s) on a serving plate or foil covered board while still quite warm and then wrap the top and sides of the layer(s) with plastic wrap. This seals in all the steam that would have otherwise escaped resulting in a very moist, but not soggy cake. Everyone always comments on how moist and delicious my cakes are and they are very surprised when they find out I use cake mixes (Duncan Hines of course)! Refrigerate the layers while still warm. This will help the layers firm up a bit. When completely cooled, the layers will be easy to frost and decorate. Let layers sit covered at room temp for 20 minutes or so before frosting. If your work area is humid, let the layers sit a little longer so the condensation will form on the plastic wrap and not on the cake itself. Remove plastic wrap and frost and decorate as desired.
Reynolds Non-Stick Aluminum Foil is a great way to get your brownies or bar cookies out of the pan easily. Line your baking pan with the foil, leaving an inch of overhang on each end of the pan. No baking spray or greasing needed! After the brownies have baked and cooled completely, use the foil to lift the brownies out of the pan and then cut into squares.