What I've learned about taking photographs of butterflies:
1. Try and photograph the butterflies from many different angles. Allowing yourself to capture the underbelly, for example, is quite interesting because you get to see the butterfly in a more "real" way.
2. Take the photograph immediately when the butterfly lands on the flowers. At this moment, their wings are spread openly which will allow you to capture their beautiful pattern. If you wait any longer, the butterfly will close its wings, camouflage into the bushes, and look just like a leaf (smart evolutionary move).
3. Take a moment to stop taking photos and watch how the butterflies feed. I must say, it's fascinating :)