well I think you already answered your question - she can take some classes with your friend who is a bellydance teacher! :)

I think most people here would agree that a lot of gothic bellydance comes from a personal style: taking the bellydance skills you already have and blending those with the look, music, and atmosphere of your choosing. Have her continue her dancing and take it in her own direction.

That being said, there is a video I like to share with friends considering making the plunge. Tempest did a video for WordDance New York called "Belly Dance for Beautiful Freaks" that is very useful. She covers a lot of topics, from how to modify your movements to work in platform boots to how to capture fun evil expressions. Plus she teaches dance movements to Skinny Puppy, and you can't beat that.

www.darklydramatic.com/tempest/bdbf.html

Ariellah and Ashara both also have videos through WorldDance that have a heavy goth flair, but Tempest's is the only one that really discusses style, and I would highly recommend it for her.