I'm not a professional. I haven't taken a baking class. I learned my baking skills from my family, trial and error, and lots of books. Plus, I'm not perfect. I learn new things every day and I love to get new baking information from folks. So, I want to impart some of the wisdom I have learned from those far wiser than me. So, I hope these help:
1. Fill your cupcake liners no more than 1/2 to 2/3 full. I have to stick with 1/2 full as I always overfill my cupcakes. You don't want them to overflow and get messy.
2. Don't overmix your batter. Over mixing can cause your cupcakes to end up chewy instead of nice and moist. Follow the directions in the recipe.
3. Bring all ingredients to room temperature before mixing your cupcake batter. By mixing cold items into your batter, you risk having a lumpy batter which might cause you to over mix your batter. If at room temperature the ingredients will mix evenly and the result will be a wonderful cupcake batter. Same goes for icing. Don't put cold milk into room temp. butter!
4. Cook only one pan of cupcakes at a time and rotate the pan. You want your cupcake pan in the center of your oven. If your oven tends to cook items more that are toward the bake, then rotate your cupcake pan halfway through the cooking time. If you are cooking two pans, make sure you switch the pans halfway through. This will ensure that you get evenly cooked cupcakes.
5. Use a small offset spatula for decorating. It has a flat rounded blade designed for even spreading. The crooked handle gives you extra leverage.