I don't know if these will be helpful since I don't use GIMP but they look pretty detailed to me.
Coloring a B/W Sketch
GIMP Coloring Tutorial

Short Story/Book Recs:
D.H. Lawrence - The Rocking Horse Winner (short story)
Nikolai Gogol - The Overcoat (short story)
Albert Camus - The Stranger
Alain de Botton - On Love: A Novel
Jon Krakauer - Under the Banner of Heaven (nonfiction)
Ben Mezrich - Bringing Down the House (the true story that the movie 21 is based on)
Amy Tan - Saving Fish From Drowning (fiction)