Pick Advice Needed

I am a folk guitar player who uses bare fingers or thumb and finger pick - rarely strumming and never with a flat pick.  So as I start to learn to play the dulcimer, I'm trying to find the best weight flat pick.  I've found that those on the lighter side (.38 or so) are easiest to use, but of course I get the annoying clicking sound.  Anything much heavier and I can't seem to get the 'bum diddy bum' to work.  Any suggestions?  Thanks