Helpful Tips for New Players
So I've noticed that alot of people are having problems with the game mostly due to the bad controls/gameplay mechanics. After playing through the game 4 times (which is something you have to do for the "Bird of the Different Feather" achievement), I've come up some good tips to help you get used to how to the controls work which can help you get through some of the more difficult parts of the game.
1) Pressing "Up" on the right stick makes you accelerate really fast forward (by performing a corkscrew) and helps you keep that momentum. This is really helpful in those missions where you have to get from one point to another quickly or during the races. However doing so consumes one bar of your meter (on the top right screen) so building meter constantly is important which leads me to...
2) How to build meter. Which is done by either collecting coins or by flying downwards. When you fly downwards you build meter which can be used to perform that corkscrew attack or command your teammates to attack enemies. If you ever find yourself losing momentum and out of meter, flying downwards helps alot to build that meter so you can use that corkscrew move again.
3) As far as combat goes, your best bet is to use the "Y" "Y" "Y" "X" combo as that will usually kill most enemies in one combo. Some of the more advanced enemies will counter you after the second "Y" so its best to do a grab move (by pressing "B") after the second "Y" and aiming them at the ground for some extra damage.
4) Pressing down on the rightstick will make your owl turn 180 degrees which is 100 times easier to do then trying to turn normally. This is especially true for those missions where you have to grab a piece of fire to throw at the towers or siege weapons.
Hope this helps. Once you get use to the proper way of accelerating and combat the game becomes really simple and easy to play through. You might need some practice to get gold on some of the missions but by my 3rd and 4th playthrough I was able to get gold easily on any mission with the two slowest birds in the game.