I figured it was time for a non-cataloging related post.
The edited image is made up of 5 layers (actually 6, but only 5 of them make up the visible parts of the image - I kept the original image as a background layer that I could copy in order to create additional layers).
Originally, I tried using the "cartoon" filter to create the black lines I wanted, but I didn't entirely like the results and the filter, however nice, didn't give me enough control. Since I'm still limited almost entirely to using a touchpad, I don't have much fine editing ability, either.
I created an effect similar to the cartoon filter by copying the original image and applying the photocopy filter. Then I selected according to color and selected all the true black areas of the layer with the photocopy filter applied. I inverted the selection, cut everything that was selected, and then made the selected area transparent. I repeated those steps with another layer with the photocopy filter applied, only this time I selected gray areas. I repeated the steps again for another gray. For all those layers, I made the remaining ares of color (the lines leftover from the photocopy filter) completely black, either with levels or with the colorify tool.
Then I decided to mess with color. I may not wear them, but I love bright colors, so I created a new layer and used the Color Balance tool until I got something I liked. However, I only really liked it on my shirt, so I deleted and made transparent every part of that layer but the shirt.
I still wanted to punch up the rest of the colors in the picture, though, so I created another layer and used, I think, the Hue-Saturation tool until I got something I liked. I thought I'd end up doing the walls separately from my face, but I ended up liking that particular color effect on both areas. However, my face had gotten a bit patchy-looking, and I wanted to smooth that out. I tried out a few tools but ended up liking the Oilify filter the best.
I didn't entirely like the hard lines (the result of the stuff I did with the photocopy layers) along my jawline, some areas near my mouth, and on my neck, so I used the eraser tool to get rid of those. I can do that much, even with a touchpad.
And that's basically how I did that image. It's nice to know that I can still use GIMP a little, even with a touchpad - there are just a few limits to what I can do. Drawing in GIMP, no, but editing a photograph? That I can do.
Also: yes, my NaNoWriMo novel is not going well. As has happened every time I've taken part, my writing speed has tanked. I'm hoping I can get it back up again - there are still several weeks left in the month.