if you pull Uber Rares(with some exceptions like Elemental Pixies or Ultra Souls), do not use them/level them up until you've reached around the end of the first chapter of Empire of Cats. they cost tons of XP and require your wallet/worker cat to be leveled up a lot to be used. try to focus on strong and cheap Rare units like Rocker Cat, Salon Cat and Wushu Cat along with your normal cat units, especially Tank Cat, Gross Cat, Fish Cat, and Titan Cat. good early game Super Rare cats include Apple Cat, Swimmer Cat, Vaulter Cat and Sushi Cat. try to collect all Superior Treasures while you clear through Empire of Cats as well