Your grasp of anatomy looks pretty good - it looks like you're using photo references for poses and such, and I'm a big fan of references. Try not to be too reliant on them, though - as an exercise, try taking a photo reference of a pose, and then draw the same pose from a quarter-circle to the left or right, or a slightly higher or lower point of view. It helps to understand how things exist in three dimensions, which will ultimately reduce your need for references.
Pumping up the contrast between highlights and shadows would help make things look a bit less flat - especially where you're using textures for stuff like hair and tree bark. Digital texturing can save a lot of time when it comes to rendering background elements, but at the moment the combination of fairly stylised solid black linework and intricate digital textures seems rather jarring to me - especially when the background is a Photoshop filter that doesn't really seem to bear any relationship to what's going on.
I'd recommend trying to vary the line-width a bit more as you draw - a thicker line for the silhouette outlines of objects to make them pop from the background, and a slightly thinner line for details inside that outline.
I'd also recommend dropping or at least toning back the Photoshop texture filters, as at the moment it seems that they're being used as a stand-in for drawing backgrounds. It's a time-saver, but it can become a crutch.
To help with shading, try experimenting with a cel-shading kind of approach - rather than a blurry soft-edged brush, try dividing up an object into crisp-edged highlights, midtones and shadows to get a feel for how the light falls.
Hope that helps - there's definite enthusiasm and promise in what you're doing, but it's my opinion that at the moment you're relying on your tools more than you're relying on yourself.
