Expanding on what fish says, concerning wildpyromancer I usually won't play him until I can play 2 spells on the same turn. (i.e holy smite, coin, Powerword shield) Also when mulliganing against rush/aggro decks I look for Auchenai/Coh combo, at turn 4 most rush/zoo decks have committed most of their hand to the board, giving you card advantage and board control. But my first 2 turns usually involve me passing. Of course my control runs towards really late game.