"Angry Birds" Basics
The objective of "Angry Birds" is to defeat all of the pigs in each level; this is accomplished by throwing different colored birds at them using a slingshot. When all of the pigs in a level are defeated, you are given a score. This score determines your ranking on the level, which can be anywhere from one to three stars. Each level has different requirements necessary to get two or three stars; one star is automatically awarded just by completing the level. You can also find Golden Eggs hidden in a few levels; when found, you gain access to a bonus level.
Use Fewer Birds
One of the best ways to increase your score is to use fewer birds per level. Most levels can be completed by using only one or two birds; most of the time, you are given anywhere from three to five birds to complete the level. Any remaining birds add 10,000 points apiece to your overall score. By completing the level with as few birds as possible, you increase your chances to obtain three stars on each level.
Destroy the Level
While your primary objective should be destroying the pigs using as few birds as possible, also try to destroy as many objects as you can. The pigs are generally resting atop or inside structures made of wood, ice or concrete; each time any piece of these structures is destroyed, you gain 500 points. If there is a TNT box on the level, try and aim a bird for it -- not only will you destroy a few pigs in the process, but you'll also destroy much of the level -- leading to an increase in score.
Know Each Bird
Each bird has a different strength and weakness depending on its color. For example, tapping the screen while the yellow bird is midair gives him a burst of speed, turning him into a missile; this is good for destroying ice and wood structures but won't work against concrete. There are five different birds in "Angry Birds" and the game provides a tutorial for each one to let you know what they can accomplish. The game decides the order of the birds; often, the first bird's strengths and weaknesses are a clue to how to approach the level, allowing you to complete it faster and earn more points.
Golden Eggs Stars
The Golden Egg levels, unlocked by finding Golden Eggs during play, do not use the three-star format the rest of the game does. There is only one star to get in the Golden Egg levels; it is awarded simply by beating the level. However, the Golden Egg levels are more puzzle-based than the rest of the game; you are generally given one bird that must be flung at a particular spot to destroy all the pigs. Knowing the strengths and weaknesses of each bird comes into play heavily during these levels.