This picture isn’t so bad, except for the fact that one hand is way too big. In other words, that one hand isn’t proportional to the rest if the body or the other hand. Both arms,hands and legs have to be the same size and length as the other.
 
The are only two exceptions. One is in cartoons when you are exaggerating them on purpose (and even then you still have to maintain some kind of consistency in your drawing). The other exception is when dealing with perspective. If your characters hand,foot,head is closer to the camera/viewer then it gets bigger. If the hand, head, foot etc is further and further away from the camera/viewer then it gets smaller and smaller.  
Try to think of your paper as a window into another dimension-through which you look at your characters,objects and scenery.  
 
Here’s an example of perspective. Try looking it up and learning about it. For this I recommend Ernest Norling perspective drawing.