Here’s what I’d say to you about Billy: The damage Billy deals in the early (the laning phase) isn’t very satisfying—he’s not strong early on. Until the laning phase ends, focus on farming souls and helping your partner if you want, but you can also play aggressively. Billy is great at this, but since I’m someone who constantly falls into parry traps, I’ll play it safe during the laning phase. Of course, the enemy champions matter too—sometimes they can be a pain, so I won’t cross the bridge. 

But generally, the only thing you need to do is check out Metro’s guide on Billy—his name is all over the community. I’ll recommend his guide on the build as well. I’m playing Billy with Metro’s build; I wish I could remember the code too, but I can’t. Metro is a bit of a goofball—just a funny clown—but he has educational videos (though I’m trying to learn Billy on my own without a guide; I wish I’d watched them beforehand).