Hint 1: Save all your money until you can afford Score X8 and buy it. This will make it easier to buy the rest of the stuff.
Hint 2: Do not buy cheapest item to most expensive. The more expensive, the better in looks and power.
Hint 3: Do not buy any form of Poison Ivy first, they all stink!
Hint 4: For more money, get True Hero or True Villain in a level.
Hint 5: Trust me, to win Gotham Skies Villain minigame, you will have to use the turbo!