I'm guessing you're doing this for a test and not for a competition

I haven't tested but I have competed in artistic/interpretive.
Choose a piece of music that you really like and that has some variety in it - not necessarily tempo, although that's good too, but in mood or dynamics. If you're editing a longer piece, make sure that the shorter piece sounds like a complete piece in itself, i.e. no unexpected changes that sound odd. If you're using music with lyrics, be sure that the vocals are clear, as in someone who hasn't heard the piece before being able to understand the words.
For the choreography, obviously it has to reflect the mood or story of the music. But think about variety in edges, turns, and direction, and also variety in levels - not just skating upright all the time, but reaching/leaning up, down, to the sides. Interesting body "shapes" (for lack of a better word) really work well. Good flow, speed, and ice coverage are things the judges look for as well. Even if you're skating to a slow piece, you can still move at a good pace while respecting the music.
A lot of adults do interpretive/artistic programs to GFBs (generic female ballads) or to an upbeat Top 40 hit, which I guess is OK if that's what floats your boat. But IMO the more interesting programs are the ones that push the skater to do something more challenging or unusual. Interpretive/artistic can be more than "my heart is broken" or "woo! let's party!"