Look in your pantry. What kind of flour do you have? You may have probably all-purpose or self-rising flour, but if you are an experienced baker, then you probably have cake flour as well. The general rule is that self-rising is for bread and muffins, all-purpose flour is for mostly everything else, and cake flour is when you want to bake a special cake or cupcakes.
The gluten in wheat flour provides the protein. The protein is the flour gives baked goods their structure. That's why self-rising flour is better for breads and muffins because it has more protein.
All-purpose flour works fine for cupcake baking, but not all-purpose flour has the same percentage of protein. A softer flour with less protein yields a lighter cake. Look for flours that have lower protein content than self-rising flour. Gold Medal, King Arthur Flour, Pillsbury Swan's Down and White Lily are brands that you want to check out. Swan's Down and White Lily are regional flours. They may not be sold at your local grocery store, but you can find it online.
Cake flour is also good for cake and cupcake baking. The goal for cupcakes is a light airy cake, not a dense cake. Cake flour is often sifted more than all-purpose flour in processing.
Most cupcake recipes call for either all-purpose or cake flour, and many advise to sift the flour with It is a good idea to sift the flour even if the recipe instructions do not for call it. Sifting the flour is a way to lighten the flour that has been densely packed. I remember sifting flour for my Grandmother when she baked cakes, but I don't have a sifter. If you are like me and don't have a sifter, then you can use can a sifter or a colander to sift the flour.
There are alternatives to wheat flour if you want to bake gluten free cupcakes, but you must be knowledgeable about the different flours. Not all wheat free flour is also gluten free. Gluten free expert Shauna Ahern suggests combining several flours together to make your baking flour. If you are not up for that there are gluten-free baking mixes available at grocery stores and health food store.
Lastly, weigh your flour if you can. Invest in a digital scale and use that to measure out your flour needed in the recipe. This will yield a more accurate measurement and loosen up the flour which is densely packed when packaged.
Remember this: Baking is not just a science. Baking is chemistry. So it is important to know how ingredients interact with each other.