Derek (Ricky Gervais) Bamboo Tile Portrait

This is a bamboo tile about 3/4" x 1.5". I bought these a while ago intending to do miniature portraits on them and put them on necklaces, but I've been so busy with other things that I just got around to working on them. I sanded the finish off and put on a light layer of white gesso. We've been watching Ricky Gervais' show Derek on Netflix. It's our new thing to quote around the house. As in "do you want to do this?" "Definitely, it's my best thing!" So I've decided to give Derek's portrait a go.
Being that it's so small, I have to use very small and pointy brushes. And the smallest error makes the whole thing look wrong. Like here, the eyes are too high up. I will have to try again.