Hi there, I think you've got some good advice above and you are doing a great job. I would have advised to use some transparent base and light layers, as well. Comparing your reference to your project, you will notice that the white edges from the corner of the dog's eye to his muzzle and on his/her left side are a bit too wide. I would push them back with some transparent paint. Again, layers, layers, layers. I think the ear's edge is a bit too sharp, I would soften that a bit. When looking at your reference, notice that the white areas of the fur above the eye are a bit foggy. I would do some light dagger strokes with your dark color back into the white to get rid of the fog. In the reference those white areas are a bit more sharp. Its a back and forth push and pull with the white and the dark until you get the results you need. Patience is key. Take your time. I'm not sure what surface you are working with. Can you erase easy? I hope you find this helpful.