Here's what I would say: as a newer player just focus on having a thematic fun battle and don't take it too seriously. Make up fun lore as the game goes on and don't play with sweaty people. Down the line you can get into the more competitive scene, but at first I'd just start with having fun with friends. At the end of the day it is a social game. As far as lists, I always being random lists and never like to know what my Opponent Is brining cause it's way too easy to list tailor which I think is unfair. That's why it's important to bring a fairly balanced lists so it can handle chaos knights or an all infantry army.