I heartily concur with Elmstreetart and monkeybread's post. I'll add a few of my 2 cent's worth experience:
I'll share with you the process I made for one year where I wanted to boost up my drawing skills. (If I had more time I'll still keep practise drills like that).
-2 hours of artistic anatomy study a day. Find a VERY good book on human antomy, (learn from the best, forget flashy anatomy books with gorgeous photos of play boy and girls, plus some books don't present the correct info in a correct way), and learn the human body from the bottom up. Start with the bones, than work your way to muscles when you have finished learning bones. Learn the major difference between male and female body, (there are some, especially on the bone level). Learn that so it becomes a second nature when you look at someone... Human body is a machine, and even if we are all different, we are all build up on the same basic structure, (which comes in handy when needing surgery). Regularity is important here to learn.
-Ideally, you should do the same with animal anatomy, but since there's a great deal of animals, learn the generalities of animal anatomy. Again, find some good books.
-Life drawing, sketchbook from life. This is THE killer thing. Draw peoples outside, draw stuff in your appartment, from the streets, draw everything. Observe. In fact, is there's something you haven't draw yet, that's a clue. (For example, I have been doing life classes every week since almost 10 years now, and I was up to 9 hours a week of life drawing session last 2 years... It helps!)
Along side with anatomy and life sketch, you should get and read Mike Mattesi's books on drawing with force: get the one on dynamic life drawing and animal anatomy. With these and classical anatomy study I'll say it's allready a good way upstart...^^
-Perspective. Learn the basics and find out about the cone of vision. F** important the cone of vision.
As for value, matt khor released a very good series of worksheets on his site, ctrl-paint, about form, perspective, light, color and composition. They are actually very good. And of course, gurney's book.
And finally, do illustrations, storyboards, comic book pages along with your studies. Look at movies, graphic novels and classical illustration/paintings, just to devellop your narratice sense. The best ever drawing school I know is doing comic book/ graphic novels pages, cause you have to draw just about everything: characters, environments, props, story, color if you make some...
And finally, draw. Every day. Every-darn-day!
And remember to have fun and to accept mistakes, that's the most important part!
Have fun! Post up your new stuff!
EDIT: I forgot, here are some online ressouces that you might find usefull. If not golden. (I do.)
http://www.youtube.com/watch?v=wgDNDOKnA...r_embedded
feng zhu channel's, tons of priceless info here:
https://www.youtube.com/user/FZDSCHOOL?feature=
propopenko on loomis's method for head:
https://www.youtube.com/playlist?list=UU...23462tQzBg
and of course, as I mentionned before:
http://ctrlpaint.com/
