First of all I'd like to say from what I've seen in this thread your drawings so far are really good. You're probably a lot better than me in terms of fundamentals, I can't even copy anything if I wanted to. I really liked your Miku drawing a couple pages back. You should really continue that Ritsuko drawing too, it was off to a great start! Looking through all these drawings are really getting me inspired and motivated, I'll have to make time to draw some today too.
I really need to draw more. Can you give me any tips on how to be more motvated? I find myself listening to music and surfing the web when I could be drawing. 
Motivation is really a big problem for me as well. Especially since I'm uncompromisingly impatient. When I start a drawing I'm already looking for ways to finish it. No pacing what so ever. So a good way I've learned of getting more drawing done is by timing myself, I set aside maybe 15-30 minutes every day to draw, and only to draw. Within those 15-30 minutes set benchmarks or checkpoints. For example: @5min (gesture, action line) @10min (initial sketch, proportions etc...) @15min (secondary sketch, laying in the body musculature, details etc...) @25min (add clothing finish up) @30 (wrap up the drawing). < Just an example outline, you can make up your own benchmarks/checkpoints to suit your own technique and method.
When you do this I think it helps build the habit, and you won't have to motivate yourself
as much anymore. Granted, there will be some days where you won't feel like drawing at all. However, those days are the days most important/crucial for you to draw on. If you don't draw on those days, I find it, you won't feel like drawing on the next, and it becomes harder and harder to get back into it. You have to keep drawing!!!! That is probably the best advice I can give since I'm not that far along on the drawing journey myself, but I hope it helps. ^^