We have always played "the traditional style" as explained in "The Dulcimer Book" by Jean Ritchie. That means strumming with a pick and using a noter in the left hand. It's an excellent book and, if you want to learn that style, will teach you everything you need to know. It's been in print for about forty years and you can still get it on Amazon or other places. You can probably find it at Foyles next time you're in London.

Bev and Jerry