The below image was for the American Diabetes Association magazine, another long-time client I haven't worked for recently. DC has associations of every description (there's even an Association of Association Executives) and all of them have or had a magazine or newsletter that used freelance illustrators. You could build a pretty good career working for them, and before I got more into purer (ha!) cartooning, I did a lot of work for them, almost as much as I did for the Post.
This is in alkyd too. Alkyds are somewhat like oils, though their texture is a little tarrier they thin with turpentine, but they use a resin instead of linseed oil as the vehicle for the pigment. They also dry faster than oil and you can use them on paper, which oil will eventual corrode. So they're well-suited for illustration work. The way I used them was this; I'd draw a rough in ink on a thin, semi-translucent layout paper called Ad Art, once made by Beinfang (but alas, no longer, I loved that paper), put another piece of Ad Art paper on top and draw a more finished (but still loose enough) final, then spray mount it on a piece of 2-ply Bristol board (it had to be pliable to fit on a drum for scanning). Then I'd put a first layer of alkyd using Winsor & Newton Liquin (a thixotropic alkyd gel medium) mixed with some warm tint, like an ochre or something, and work some details a little with colored pencil, which would somewhat liquify and mix with the Liquin. Then I'd let it dry, maybe spraying it with Krylon, and do another layer of color and another, etc, building up a bunch of glazes, which gave it a nice depth. And what did I use to put the alkyds on the paper? My favorite tool was a little wad of the spongy foam rubber they put under wall to wall carpeting; I had a giant roll of it and I'd just tear off a suitable piece. That and Q-tips. Silly as it sounds, it wasn't too different from what others have used over the years. Casein paint, a milk-based paint, would stick well to the Krylon (if it was matte Krylon) and was useful for detail work, like the red threads in the sewing machine in the image above. When it was finished I'd have a pretty snappy looking little painted art objet. But it was time-consuming and smelly and messy, none of which you want on a deadline. And when we suddenly had a baby around, I wanted something less toxic.
I'd been leery of watercolor for years as I thought they were difficult and unforgiving. So I started with them fairly slow and easy, using only a few colors, a couple of warm colors and a blue maybe. The first watercolor I did under a deadline was a little drawing of Colin Powell for the New Yorker; it had maybe 3 colors in it and looked just fine. I learned a few simple rules and tricks. All colors handle somewhat differently, especially in a medium with the immediacy of watercolor, and as you use them their personalities reveal themselves. I still don't know exactly what I'm doing, but nobody's caught on yet, and I'd appreciate it if you didn't tell them.
This has been your art lesson for today.