*The last big issue, which I know can be hard to help with. He looks to young, even though I think it is partly because of my personal style I would like him to look
A bit more like 21 and not like 12. Tried to make his legs longer, shoulders wider, even tried changing the outline of the face but he still looks like a kid.
Firstly I have to ask... do you ride?
Secondly... the reason why you look so young is the proportions of the head to the rest of the body... which is (as many others will happily point out) is suffering from severe animangaitus - a common disease that many artists appear to suffer from... such is the way of things.
May I suggest you adapt your 'personal style' to something more... well... personal... and not what everyone else does? What happened to individualism?
I don't know... perhaps thats a bit harsh... but one tends to bore of Manga stuff after a while...
Try shrinking the head to fit the body more in keeping with correct proportions for an adult... and try and render the face less Akira and more Illsnidig...
Also, the pallettes really rough, you need to try and make it less contrasting... and learn to anti alias.
On a postive note... the pose is kinda ok and the lines are pretty good...
it's just that animangaitus you need to take some pills for I think...