Here is a basic tutorial for male anatomy.You picture sucks because you're doing what millions of others try to do when they draw, you're freehanding it.
The reason why professionals get nice pretty proportional people is because they sketch things out in layers.
First you make a stick skeleton of the pose you want using circles for joints and lines for limbs, get your size proportions in here.
Then you draw the bulk shape of what you want your character to be around that "skeleton".
Next, draw in the final shape of your man using the shapes as a guide.
By this point, you sketch will look like a mess, use a dark pencil to draw out the final outline of your character and erase everything else.
Now from here you can make him nude and finish up or sketch out clothes around his body, using the body as the guide like you did with the skeleton.