Watch the Canon in D online guitar lesson by Tony Smotherman from Classical Flatpicking Explorations
Try using the picking pattern D, U, D, U, D, U, D evenly. You'll see that this picking pattern works well, but also feel free to experiment with your own picking patterns. These shapes are a really effective way to play one octave arpeggios all across the neck. The basis of the arpeggios are simple: root, third, and fifth. Sometimes, the best things are the simplest.