Well, thats not really a new shading technique, its used by quite a few pixel artists. You should try some dithering on the pot. Outlines can either make or break things, black ones tend to usually be ugly, try using a multicolor outline if your going to use one at all, I would say the pot would look good with an outline, but the flowers are fine without it. If it looks jagged after that use some Anti Aliasing. Limiting your colors and keeping a better constant light source would be nice as well, after all pixeling is the art of using as little colors as possible while creating the illusion of using more.
Over all its a pretty nice peice.
Good work!
