Fantastic work, your proportions are looking good.
Try to have some more confidence in your lines. I see you're sometimes drawing a line in little steps instead of drawing it in one motion. It will make everything look cleaner but requires a bit of practice.
30 sec is challenging. Just think of the 8 parts of the body (head, spine, ribcage, pelvis, 2 legs, 2 arms : in this order generaly), don't try to draw the outlines of the figure, just what the figure is doing. Hope this helps :)