There really is no right or wrong way to learn that’s the beauty about it! Here are some tips I can offer you that maybe some others didn’t (sorry didnt read every response):
1) Pick up a dummy round to practice on, practice piping on the counter (shells and other tips). You will need some work on some real cakes to to get a real feel of how to decorate.
2)I also take any extra batter I have from cake orders and bake off any cakes I can with it for practicing later. Stick them in my freezer and pull out when I got extra time. I do the same with left over buttercreams and fondant. I bake different varieties of shapes but my mini cake pans get the most action with left over cake batter. ALOT of my cakes are practice cakes, that’s when I try a new technique I really been thinking about or work on something that I need more practice with. I dump these cakes after I’m done playing around, I just pretend I baked them for Oscar the Grouch so I dont feel as bad for dumping them in the trash right after. :)
ANd I agree with everyone above, the internet is a great source to learn from, practice and pick up some books to if you can! HTH and good luck!