To really little me: "Don't hurt any animals. Just don't. Even the ones you're afraid of, like spiders or centipedes, because they're not even dangerous and you'll feel really guilty for it later if you do. And, hey, you like those Redwall books, right? Well, if you need to, go to the school library, pick out a nice copy of Mariel of Redwall, go to Chapter 4, and read the Abbey Charter. You see that bit, the part that says '... forsaking all unnecessary forms of violence, not only to Mossflower, its trees, grasses, flowers and insects, but to all living creatures...'? Follow that shit, you little shit."
To teenage me: "Eh, just drop all the occult mumbo-jumbo and you'll be fine. You don't have to stop wearing the pentagram - it is pretty badass - just don't waste your time actually believing that nonsense. Simple agnosticism mixed with philosophy is probably the way to go; you don't need any sort of superstition muddying up your thoughts, even if it is the cooler and edgier kind."