1. Visual metaphor (eg, eating ships instead of sinking them)
2. Pastiche of famous painting or artwork ( Bell's version of Toulouse-Lautrec, Gillray's Three Witches)
3. Anthropomorphism (eg Pit the mushroom, Ed Milipanda)
4 "Angry", expressive dip pen and ink line, splatters, etc, contrasted with regular forms such as concentric circles for eyes (Scarfe, Steadman)
5. Emphasis of facial features (classic caricature)See: http://www.tomrichmond.com/2008/02/14/how-to-draw-caricatures-1-the-5-shapes/
6. Parody of plot and characters from a popular TV show, film or book (EG Star Wars)
7. 3-D caricature such as found in Spitting Image by Fluck and Law
https://www.youtube.com/watch?v=LRF6ml-J6t0