Okay, sorry if you already know some of this stuff, but the basics are the most important thing.
First of, try to make sure when you photograph that your pictures are in focus, on most compact and bridgecameras all you have to do is slightly press the button and it will automatically focus. Also take your photographs straight on, now they're often at an angle so they look distorted. Try to have as much light as possible when you're taking the photos.
The drawings are not bad. Something you might work on is construction, proportion and symetry.
With symetry and proprtions I mean on some drawings the left arm is longer/thicker then the right and things like that. They should be as long (unless you're making an assymetrical character).
Proportion just means the way how long/large/etc things are in relation to eachother. So when your leg is two heads long, the other leg should be as long also, keeping in mind it would get smaller as it's further back because of perspective.
With construction I mean that the shapes are sometimes a little inconsistent.
Polykarbon Male Figure Tutorial <- Here's a tutorial that shows a way of dealing with proportions and construction.
Some videos of Adam Hughes about how he draws a character.
Keep in mind that constructive drawing like this can be both a way to learn as a way to draw. With that I mean that it's good practice to draw like this allot so you'll get a good understanding of form, but at the same time if you've done it enough (and you'll need to do it ALLOT) you can manage without it.
2 good books for this are the
Vilppu Drawing Manual because it deals with construction a fair bit. And Bridgman's
Constructive Anatomy.
The Bridgman anatomy books are really good because they deal with anatomy in a more abstracted way. Making them easier to draw from memory and because they give a great sense of solidity and understanding.
So try doing allot of this stuff. Making up characters build out of circles, elipses, spheres, boxes, cillinders, etc...
And keep a sketchbook to draw from life. The best way to know if you're doing something wrong or right is to look at it in real life.