As an Inkscape user (and Corel Draw before that), vector art is definitely different than raster graphics. You're doing well though!
Your comments seemed to be aimed at osiaslemuel's image, but would you mind commenting on the ones I've attached to this post?
The ghost is from a tutorial, but I made a few modifications.
The orange mushroom was just another attempt at getting a cool video game mushroom.
The red-and-orange mushroom style character is something I did on my own, using the fourth picture (the green mushroom character) as a reference. Do you think I did a reasonable job recreating the feel of the green mushroom? I had to figure out all my own techniques as I went, but I feel like it actually came out quite well (by my rather low standards.)
Feedback on any of my efforts is appreciated.