In the first one the aperture is too wide, and the shutter speed too slow. The softness will be partly down to slight camera shake, and partly because of the very small aperture, which starts having a negative effect above about f16. As a rule of thumb, most mere mortals can hand hold at a shutter speeds of 1/(effective focal length). That means that for the top photo, at 18mm, you would need 1/(1.6x18), which round up to about 1/30th second (the 1.6 is the magnification factor inherent in the 400D body). So, to cut a long story short, as Rasputin said, an aperture of f11 and the corresponding higher shutter speed would've given you a sharp shot.
The eyes in the second pic are slightly out of focus. Look at the strands of hair to the right, and you'll see they're in perfect focus. In this case your aperture is very wide, meaning your depth of field is shallow, and you have to be super careful with focussing. Again, I have to agree with Rasputin - use a slightly longer focal length for portraits.