Things like this wouldn't work in Games forum, even if it's about a game. Putting it in the Megathread would just get flooded out. Might work as a disorganized anti-noob list.
Don't waste your pickaxe on dirt. (Original Yogscast episodes)
Items despawn over time, don't leave them laying around. (Original Yogscast episodes)
Don't empty your inventory of good items onto the ground thinking they'll still be there later, they won't. (Original Yogscast episodes)
Pay attention. Pay loving attention. If you literally only see within the first 6 pixels from the center of the game screen, you need help. (Original Yogscast episodes (How they constantly miss Creepers they walk RIGHT next to somehow.))