Patience is a virtue! Particularly in baking. I'll never forget witnessing an especially efficient friend of mine who couldn't wait for her freshly baked cake to cool. She slathered on the frosting anyway and stuck it under a cake dome. The dome steamed up and the frosting slid right off!
Make sure all ingredients are at room temperature before you begin your recipe, because they will combine much more easily. Adding cold butter and buttermilk will result in a grainy, lumpy batter, which will tend to encourage overmixing. A no-no in baking!
Entertaining? Pick up dinner, but make dessert! There are plenty of great places to pick up gourmet food these days, but it's still hard to find a fantastic dessert. Dessert is the last impression you will make on your dinner guests, so take the extra time and bake something special.
Use the best ingredients you can find! There are so few ingredients in desserts that each ingredient really matters. Gone are the days when bakers chocolate did the trick. We have all developed more sophisticated palettes and the local grocery store is stocked with a world of choice beyond the old standbys. Make sure you are working with the freshest butter and eggs, the finest chocolate and cocoa, pure vanilla and fresh zests, etc.
Presentation is key. Even a casual dessert can be a showstopper when presented the right way. When cupcakes are tiered, they go from a kids treat to a grown up dessert that can stand in for a wedding cake. Tiered cake stands work for any petite desserts. Or plate dessert individually and garnish with freshly whipped cream or colorful edible flowers.
Experiment with recipes and keep a folder of your favorites. It's amazing how many recipes are published that don't actually work, so it's always wise to experiment with a new recipe before that big dinner party. Anytime I bake something I like, I add it to my folder of favorites, along with any changes I made to the recipe (e.g.: if I added walnuts, or a teaspoon more vanilla, etc.) Over time, you'll have your very own "best-of" baking cookbook created by you! Get Sprinkles Cupcakes' recipe for Dark Chocolate Frosting.