I tried a quick round of generic characters to test out a working method I've seen a couple other students/folks working with. I don't find it terribly efficient for someone with a lackluster design sense, such as myself, but it was definitely fun.
I chose a very loose theme of found-object samurai and just dove in. No reference search, no forethought.
Slapped these guys down in 45 minutes or so using a nearly uncontrollable chalk to rough in silhouettes, then a standard round to imply design and some value.
Chose four to take forward and further refined their values and general design. I'm intentionally staying in a very mid range, erring on the side of higher values.
Chose two more (rather, the other two turned out even more retarded than intended) and used my low mids and darks to push and pull the designs, as well as turning the forms a bit in some areas. Used my high values to further establish the light source.
I'll post final roughs as soon as I get a chance to finish them up. Hope you enjoyed my nonsense ;p