Not taking the quality of the chocolate into consideration

Many people wonder if it makes a difference what kind of chocolate you use if you're only going to mix it with a few other ingredients when baking. It would seem wise to avoid using an ingredient in baking that you wouldn't eat on its own. Use chocolate with a minimal ingredient list if at all possible. A warning sign is anything placed on top of cacao, cocoa butter, sugar, and sporadically, milk powder. If the chocolate in your ganache splits, it may be because the chocolate was prepared with fat and oil, which is useless while melting or tempering it. This does not imply, however, that you should constantly spend money on a high-quality bar of chocolate.

In general, you can get away with using practically any quality of chocolate if it is merely a supporting component and your recipe doesn't depend on it. However, if you're cooking something where chocolate is the main ingredient—think chocolate cakes, tarts, brownies, and truffles—you might want to spend some money on a variety that will be both simple to work with and delicious.