This would make an awesome tiny head. (Just tossing out a thought here.)
There is a digital portrait tutorial here on this site that has some very good info, even if you dont use the same style. I have found that more of your regular painting tips come in handy for digital "painting" than your average photoshop gimmick tutorial. If you wander through the drawing, watercolor, oil and pastel tutorials, you can find a lot of info that really helps. Here is a collection of tutorials that I have found come in handy...
Here is a nice collection of links for digital art information of all kinds. Follow some of these links and you will find lots of info.
Dont worry too much about how long it takes you to do something. (This comes from someone that creeps along at a snails pace) Just keep going at a comfortable pace. If this took two weeks to do, you are farther along than you were two weeks ago right?