Whenever I go to make a recipe it is inevitable I am missing something so I try and find a suitable substitution. Thankfully the internet is wealth of knowledge, but many times you just get the facts and miss out on the tricks to make them work out right. Making flours like cake flour is one of those cases. Sure it's easy to replace two tablespoons of flour with corn starch, but most of the time they don't mention that you need to sift them together. Another good reason to make your own flours is the cost savings, which in some stores can be half. Here are a few hacks for flour I have accumulated.
Self rising flour - For each cup of all-purpose flour, add 1 1/4 teaspoons of baking powder and 1/4 teaspoon of salt and sift five times.
Bread flour - Add 1 tablespoon of wheat gluten for every cup of white flour and sift once.
Cake flour - For every cup of flour you use, take out 2 tablespoons of the flour and
replace the 2 tablespoons of flour that you took out with two tablespoons of cornstarch.
Sift the cornstarch and flour at least five times.