Peace brings up an important point-strum over the sound hole of whatever instrument you play. One of the first things I try to teach is how different the sound can be depending upon where you strum on the instrument. I sometimes see "pros" who strum an inch or two from the bridge or over the end of the fingerboard because that is their habit. When you add a noisy pick to that, the sound-no matter how fine the instrument-can be awful.
This can be very important on a Mtn. Dulcimer, as you have a small indention where the strumming is meant to take place. The sound is altered if you don't strum there, and the fingerboard will be torn up by the pick. Nothing like paying an extra $100-200 for an ebony fingerboard just to tear it up.

I tend to use a thicker, large triangular pick with rounded corners for strumming & flat pickin' Mtn. Dulcimer-it is easier for my arthritic fingers to hang on to. I also like to fingerpick-it has a lovely tone. Sometimes I use a Psaltry bow for an interesting effect. I've also been known to use hammers meant for the hammered Dulcimer. It can be pretty wild to alternate some of these things during a contest piece, but the result can be taking first place.