1. When working with sound, be sure to match up your keyframes with your Audio waveform, not with what you hear. It will enable you to visualize what the sound is doing and where sound actually starts versus when you think it starts.
2. Try and discover all of the quirky little things after effects has to offer, be they different effects or shortcuts on your keyboard. 
3. Use the pre-compose feature. It helps keep your main composition organized and will save time in the long run.
4. Always think of your composition as a 3D world, where you can go back, forth, turn around, look up, down, etc. It will be easier to use cameras/null objets when you think in a 3D state of mind.