Most Effective Arena Strategy. Input Appreciated

Thank you for any and all input. I have the following birds/levels: Red = Card Level 8 + Party Hat + Bronze Slingshot = 10 Chuck = Card Level 7 + Party Hat + Bronze Slingshot = 9 Blues = Card Level 8 + Party Hat + Bronze Slingshot = 10 Matilda = Card Level 7 + Party Hat + Bronze Slingshot = 9 Silver = Card Level 7 + Party Hat + Bronze Slingshot = 9 Bomb = Card Level 8 + Crown + Bronze Slingshot = 11 Terence = Card Level 9 + Crown + Bronze Slingshot = 12My arena strategy has been to upgrade the crowns on bomb/terrence, since I seem to do the most consistent damage with them. I've read other posts that people recommend keeping all the birds at the same hat levels, while others advocate upgrading them for max. points per bird. I only use regular game play as a filler between free arena entry. My goal is to upgrade the flock with pearls, and the best return seems to be in the arena for now. I'm in gold league and in first place at 3-400 stars. Any thoughts on my best strategy for Arena play? Thank you!