You're not alone when it comes to true black being used. Many don't like using it as it gives it a feel of being flat in pieces. But all in all, when it comes down to it, it's personal choice and preference.

One thing I think you really need to do is work on your contrast. Helm's edit really shows that more then I can describe. Also, I think the blob is in need of some highlighting, gel takes in light much like glass, and moreso since you seem to understand, eyes. It reflects a lot of it back which gives it a bright highlight.

Also, I feel the hair having a purple tint was better, it gave it a more lively feel. The grey/brown gives off a dull look.

Her left foot I feel is in need of an angel change, it looks too uncomfortable.

Overall I think you've done a great job capturing the anime feel.

EDIT: I forgot to mention, which I'll add on about Helm's post. Ya. Pixel art, seeing as it's very small and focuses a lot of detail, contrast and colour. Make sure your gamma is right and monitor brightness and contrast are both high as they can go.

Updated the tree completely, again, the grass is just something to give a background:

Ya, it actually messed up and went down when I went to try to post this. I've gotten a lot of comments on the tree, and I guess I'm going to end up completely redoing it.

The grass was more of a quick five-second throw-together to give it all a background. I plan on adding depth to the grass with many variations, and bushes and such. Thanks for the comments!