thanks for the comments over at my SB.
as for your work, i see you do have clear ideas, just need some more practice with construction of the human form and perspective.
as for perspective issue, you can check the environment mentoring forum, where you can get some excersizes on 1,2 & 3 point perspective. personally, i like to use sketchup to construct objects that are a bit too difficult for me to create on my own, plus, it's free software.
on human figure, as it's been said, using reference goes a long way. personally i refer to posemaniacs.com if i ever get a doubt, or just random image searchs on google