Thank you!! That's very kind ^^
For harp rolls, I like to start with an arpegio that fits with or complements the harmony, in a very short span. There's a lot you can do with them, and they often come out sounding more complex than the writing them.
These tutorials really helped me:
Alex moukala: https://www.youtube.com/watch?v=wqNm26RBwUY
Zack Heyde: https://www.youtube.com/watch?v=wqNm26RBwUY