This is a form-down modeling technique.
The term form-down implies beginning with general forms and then working details into this by slicing or extruding extra geometry.
Detail-up will be dealt with in the next part.
Detail-up implies specifically detailing geometry for defined regions, then building them together to form one full mesh.
Of course, both techniques work great together, as well as with other techniques such as splines
So, you want a be a self-made man? Or woman?
You want to enjoy the exclusive confidence of knowing that every polygon, every vertex in your body comes from your own sweat and labor?
First, you'll need reference materials. In this case, they'll be easy to find. Prop up a mirror next to your monitor, take snapshots, draw or have someone draw you. We're interested in cartoonish, lower-detail material here, if you want more detail - check out the detail-up tutorial.
A self-made man!
So, you've got in touch with yourself using various graphic utensils. Great! Slap that new-found knowledge up in the background projection of an appropriate window [ctrl d].
I'll start off with a cylinder primitive with 12 sides. I start with 3 segments, but we'll be cutting more in almost immediately, so feel free to start off with more if you find it faster.
Select the end polygons. They're both have more than 4 sides, so they won't sub-patch.
I knife [shft-K] them into bite-sized pieces. If you're not exact (and who is) then grab the snap tool [Shft-G] and correct those corners.
No polys with more than 4 sides? Great. Onward.
Hit the [tab] button. You now have a sub-patched cylinder. If this is what you look like, you're in luck!
Otherwise, turn on symmetry and "onward"!
Align the polys to taste. Work from one view first, like the front.
Remember, I've got my background image for reference.