How do you guys decide what to put in your lists? I'm relatively new to Tyranids, but the more I read through the codex the more I want to buy. Every unit I'm like "Oh that's cool, I could use that in this way", for every unit! I don't have games as often as I'd like, and prior to every game I consider swapping out half the army and using a different strategy with different units! What is a boy to do?