Spare Time
Some of the levels can be difficult to complete and will require a lot of tries to pass, especially if you are aiming to get the three stars and the highest score possible. Therefore before you start playing make sure you have the spare time otherwise you will find yourself having to stop before finishing a level which will only make you even more frustrated.
Know Your Birds
Take the time to get familiar with your birds so you know their strengths and weaknesses as well as their special moves as doing so will help you during the game.
Try Different Angles
If you are having no success knocking down a structure and find yourself becoming frusturated it may be time to try different angles. Don't be afraid to hit the repeat button and learn from your mistakes.
Attacking
Always make a note of the position of your finger when you launch the bird, and the position in the air when you tap the screen to activate its special move so if the attack is successsful so you can repeat if necessary.
Creativity
Don't do everything by the book, there will be times when thinking outside of the box and using a bit of creativity will produce results. An example of this is when you have to shoot the Boomerang Bird backward and let it curve in order to hit the otherwise unreachable target.
Luck
You will discover in some of the levels that luck is needed if you are to be successful and get the 3 stars, when this is the case all you can really do is cross your fingers and hope you make a lucky shot.
Unlock Everything
When you do manage to beat the whole game you will be rewarded with extras and everything in the game including all the birds will be unlocked.