If your focus is to get this drawing perfect, then don't be afraid to scrap the current drawing and start over. There's nothing better than starting on a clean slate.
Like stated by AmbrMerlinus, you'll need to work on loosening the poses. Not just the running pose, but both poses seem a little rigid in comparison to what I have seen as great poses. I can't help explain how to fix them, it's something you'll have to find out yourself. The best way is to pick up a good, dependable art book and read it through.
As for costume design, what is it that you want to portray in the character? Is he a fighter, an engineer, a technician of sorts? What's his personality? Is he a serious fellow, a wise crack, a know-it-all ('Cause those are the vibes I'm getting from this example)? Clothing means everything when it comes to personality and occupation. It always has a sub-conscious impact on viewers.
Anyways, hope this all helps from a person who couldn't do better.
Wait... What were we talking about?