It was yoga night so I didn't work on the mosaic. But I thought I'd mention a few technical items.
I'm trying out a new adhesive – Laticrete Glass Tile Adhesive. They sent me a generous sample last month and this is the first I've tried it.It starts out a brilliant white. I've colored it for this project, using a variety of dry pigments (Gamblin & Earth Pigments Mayan series).
I'm using Matteo's method – a thicker thinset application (mine seems to be coming out around 5/8ths of an inch) which allows for more control of the "set" of the tesserae on all three axes (X, Y & Z), making it easier to use elements of different thicknesses or odd shapes and still get them level and even.
One additional benefit I've noticed is that tiny tesserae seem more securely affixed than they do with a thinner thinset application. It does use a lot more thinset which adds to the cost and the weight of the work... but that's not a huge concern for a smaller mosaic.