While the stars the drop form birds are a nice bonus, you can’t win a game without a lot more money and ammo so what you are going to need are treasure chests. They are two kinds, the silver star treasure chest and the gold star treasure chest. About every 10 to 15 seconds they open up and and give you one star. The more chests you have the more money or ammo you can collect.
When a gold or silver star drops from a flying bird or from a treasure chest you must click on it before it disappears or you lose it forever.