What fish should I add next

[clownbob]

I have a 20 gal tank with rocks, 2 pieces of coral (approx 4 inches across each), one clown fish (yellow) and one damsel fish (blue with yellow tail).
I would like to add more fish.

My thinking in this order is:

1. Cleaner shrimp

2. another clown fish (perhaps an orange one)

3. another damsel fish (blue with yellow tail)

4. Other recommendations?