It's great that you've jumped right in and you seem to have your basic proportions down pretty well and things like hands and feet actually look like hands and feet - congrats, that is my biggest problem
. But your drawings have a bit of a stiffness that tells me you're still a bit uncomfortable with it. I think you should definitely work on your anatomy, you'll come a long way quickly.
Go to Deviantart.com. Search for stock poses, male and female, and you can find some free image packs of people running, standing, jumping, hands, facial expressions, etc. You might have to dig a bit but there's some really great resources once you find them. Pick something you want to work on, might be faces, fingers, bodies, whatever. When you sit down to draw a picture copy a few of them to warm up. Do it fast or slow, pay attention to detail or just do a loose sketch. Doesn't really matter, I seem to have my moments, but just use it as an exercise to warm up. Might take up all your drawing time at first, but if you practice a bit a day you should get better just from observation. Look at the shapes that make up the body and the muscles and aim for natural poses and fluidity.
There is a really great book you can get from amazon, it's called Constructive Anatomy, and it's just a book full of anatomy sketches and really taught me how to fall back on basic shapes when something's looking wierd. I just pretty much copied all the sketches in that book over a couple of weeks and it improved my anatomy by at least 50%
Also you didn't really specify goals, whether you wanted to do trad art or digital, if you wanted to be doing amazing colouring or just hobby drawing for fun, so mark where you are and where you want to be, and work up your skills slowly. Master your sketches and get everything looking nice. Then add some flat colours to it. Move on up to adding basic lighting, and naturally you'll start creating more and more complex pieces.
And keep on doing your fun art too where you just muck around and colour and make a mess and draw whatever you want whether it looks good or terrible
. Will give you a gauge on how you're going and what you still need to sharpen up on, and give you a chance to experiment.
I hope that made some sense, I'm terrible at writing things like this. Good luck