Books from the library, youtube videos, and great tutorials on cake blogs and awesome sites like this one. Of course you can sign up for classes at a Hobby Lobby or Michael’s and other places. Covering a cake in buttercream and fondant I would think would be the first techniques you would want to learn and practice and then some piped borders, but beyond that, I personally just learned whatever interested me or a technique someone was requesting on a cake. Dummies are a great way to practice but if you start doing birthday cakes for everyone in your family and your friends you’ll soon have lots of practice on real cakes. (I prefer doing it on a real cake, even though I really don’t enjoy the whole baking process. That’s just me though.)