Most dragon pictures I've seen show a dragon neck which is covered with rounded
scales and cock's comb-like triagles on the upper side and covered with tile-like scales on the lower side.
To create the tile-like scales take a flattened roll of clay, press in
onto the underside of the dragon neck (at the point where it meets the body),
and smooth it out a bit (only on one
side). Take another flat piece of clay and press it next to the first, partly
overlapping the first piece of clay. Smooth it out a bit and continue to
add flattened clay rolls until you reach to head of your dragon.
Now, add a layer of clay to the upper side of the dragon's neck. Add flat
triagles of clay to create the spines, from the neck down to the dorsal spines
and the back spines.
To create the rounded dragon scales, press an old paint brush from
which you've removed the bristles into the clay. Create a nice pattern with it.
You don't have to cover the whole neck with scales, you can group them a bit
if you like. You can also use different sized brushes for an even more convincing