1) Be prepared
Read the recipe all the way through. Make sure you have all the ingredients and set the oven for the recommended temperature.
2) Follow directions
For example, add room temperature eggs into the creamed butter." You've added air to the butter by creaming it. This makes the butter wonderfully light and helps make a tender cake. If you add cold eggs, not room temperature eggs, the cold eggs can cause your butter to seize resulting in a flat, dense, tough cake.
Are you wondering what to do while your ingredients come to room temperature? You can try something called "mise en place." It is French for "introduction" but for chefs it means to "put in place." It is preparing all your ingredients before you introduce them to each other in the recipe. It sounds fancy, but it is simply pre-measuring your ingredients. You may have seen this being done by the chefs on Food Network.; they have all the ingredients are measured in small bowls and simply added each as the recipe calls for it.
It makes sense because it keeps you organized, and this is how most recipes are written. Recipes usually start with listing the ingredients and measurements. Then, how to combine the ingredients. And lastly, how long and at what temperature to cook the recipe.
I like the idea of mise en place; it makes me feel chef-y.
3) Check your oven temp
Investing in an oven thermometers may seem silly because the oven usually has one built in. But if you are having a problem with uneven baking, burning, or under cooking, the oven temperature could be the problem.