Well, the S has the weight in the wrong place--should usually thicken in the center. Check out other s's for examples. Also, the top right curves on the m and n taper oddly. Curves should be thickest at the sides and thinnest at top, if you are going for a vertical stress--your zero has it right. In general the letters need to be more consistent with each other.
Underware has a good tutorial on letter design
Also the wiki has some good links
http://typophile.com/wiki/Drawing_How-To
http://typophile.com/wiki/How-To
Eron
