You got some nice concepts there, but you seem to be concentrating too much on being a digital artist.
Try to become even greater with a normal, analog pencil. Do gestures, expressions, difficult geometry.
Then go back to your computer and see how much better you've become.
I definetely see some potential here.
I'm glad that you've decided to start a sketchbook. Use it as some incentive to keep drawing; the only way to get better is to practice!
You're at a stage now, where you need to train your eye. Keep drawing from life, and if life is not around, try some pictures.
If you want to be able to draw from your imagination it would also be a good idea to mix in some drawings from your imagination. But make sure to keep in mind the things you drew and learned from the life drawings.
Thanks for your comments on my apsaras drawing in the WIP and Critique sections. They're definitely helpful.
To follow on the "training the eye" thing, I suggest looking at the book "Understanding Comics" by Scott McCloud, whether you plan to draw comics or not. Libraries often have it. There's a section in there on realistic vs. iconic drawing. The iconic version of an eye (the one we all see in our head unless we pay attention) is your basic football shape. But that's not how they really look. To train the eye, we have to set aside our preconception and draw what's there. A useful exercise for this is to draw a picture of someone from a reference photo that's upside-down. (Got that from the book Drawing on the Right Side of the Brain.)
Also, here's a tip for scanning. Put a piece of blank paper behind the page you want to scan in a notebook. It keeps the image from the page behind from bleeding into your scan.
i suggest sticking with the basics, and by that i mean working out the general shapes of the human figure and constructing the basic shapes into a figure. Working on lip studies dont help much if you cant draw a normal skull.
look into buying books by andrew loomis or bridgman. Some of their works can be found only for free in pdf formate.
Hey MiniGoth, thanks for the post. Your work is good. I also thought the tree was a photo at first. Your people and anatomy are getting a lot better also(I really like the sketch of the guy with a broken nose)
The only thing I notice is the 'hairiness' of your linework, esp. in your sketches. (Just these ones, really... http://www.conceptart.org/forums/sho...55&postcount=9 )Try to get just one line down without lifting your pencil, and leave it that way, without scratching back over it again and again. Otherwise your linear work looks like it's made from straw and lollipop sticks...
Practise some Blind Contour drawings (look at a subject, but not at the page; you keep your pencil constantly on the page as you work, but don't lift it until you're done!), and do RL studies without lifting your pencil. Treat every line as if they're irreversable and set in stone. Good luck!
I'd say before you start doing digitial work first start from the basics and learn them first. Have to done the sphere and cube shading along with the composition basics yet. They help artists out a great deal try doing some simple lessons by Loomis.