This is a great snail! Nice simplification. It feels a bit complex in the area where the shell meets the body of the snail, but overall you've done very well.

This is nice! Your drawing is very pretty.

There's a lot of good here! I think your trouble is with proportion. The left eye is a little too big, as well are the lips. The only fault in shading that is see is the dark spot beneath the lips, which look more like a goatee in your drawing. The eyes could also be more on a slant, like a little more vertical from high left to lower right (does that make sense?). But you are talented. This is very well done.

Nice work! Don't have too much critique, maybe shadow 4 and 5 are a bit to much the same? I can only see 4 shades with the white of the paper included. But love the over-all pic.

Looking good! I would just recommend bringing the lips down a value, as they are naturally a touch darker than his skin and also have a cast shadow (on the upper lip and underneath the bottom lip, because the light source is coming from the upper left downwards). It always helps to squint at the image to get an idea of the main masses of value without details getting in the way, so you can see how the darkness of the lips transitions into the shadows on his face.