First, find places where birds fly, preferably in numbers, and try to identify flight paths. It is a great way to practice and maximise your chances of capturing nice photographs. Once you have found your spot, think of putting the wind at your back. Birds fly slower into the wind, thus making it easier for you to track them and keep them in focus. A tripod, or a pan head can be helpful to stabiliser your image. Last but not least, be ready to follow through and focus on keeping your bird in the frame.
Flamingos in flight, Jacques Joffre