A blobby shape is refined by redrawing pencil lines in Adobe Illustrator. The first drawing shows the original drawing in Illustrator. The second drawing shows a revised version after redrawing the left side. The third drawing is the revised version after redrawing the right side. The fourth drawing has a face and ears added to the final revised face shape. Here I have "edit selected paths" checked and "within _ pixels" set to 12. You can play around with the settings to see the different effects you can get.
When drawing in Illustrator, I usually use the pencil. I like that you can adjust lines that are selected by redrawing them. The old line is then automatically replaced with the new one. This is a lot faster than erasing and redrawing with a pencil and paper. It only works for new lines or lines selected with the arrow tool that are within the distance you have set in the pencil tool preferences. (Double click on pencil tool or hit "enter" on keyboard when pencil tool is active to bring up the pencil tool preferences.) You can also manually select any line, and the pencil tool can then redraw it.