Correct Me -Annie Non

so this is my first time red lining someone elses work, but I wanted to give it a try so bear with me.
I've broken it down into steps and hopefully you can see what I was doing on each

Firstly, like you mentioned the posture is quite blocky which I have to agree, the body is very very stiff and I can assume you didn't use a reference. 
A good way to help with posture and posing (especially for simple static poses like this) is to find a stock image to reference, even for more dramatic and complicated poses there are many stock images out there you can use for instance SenshiStock has tons of useful images.
So after you get a reference copy the basic posture (after doing this for a while you can just eyeball the picture) when we compare the redline posture of the original picture to the referenced one we can see the difference in the hip to shoulder position, this is something that helps posture look more natural your hips and shoulders should move like this o\-/=  o/-\= pretend they are bodies haha one side is pointing away from each other and the other side are pointing at each other, this is something that especially comes in to play when drawing walking and hand on hip poses (unless they are standing straight of course) you should try some exercises like this kada-bura.tumblr.com/post/8702…

as for hands and faces, the face was actually good proportions wise everything was in the right place it was just the jaw was to fin and the cheek was too flat. The hand you could have made okay in just a few steps  here I've broken the hand down into 4 parts - palm, wrist, thumb and fingers. I'm still no expert at this, but this is one of the easier ways to get the shapes down. once you've drawn the basic shapes all you have to do is draw in 3 lines to cut up the block where the fingers are and that gives you your basic shape to then go over. 
Don't worry about perfection at this stage, you're still learning and there are hurdles we all had to jump over. Focus on one thing at a time and practice. As you can see from this picture I broke the image down into 5 steps each time adjusting bits here and there.

hope this helps.
for KizoraDuLonite