Making the jump to digital artwork has been a big shift in thinking for me, in many ways, and there's a lot to comment on about the differences, but here are some specific thoughts on sketching in a digital environment:
The digital sketchbook
I've always been a big believer in keeping a sketchbook, of concepts, ideas, roughs, etc. I think drawing should be a daily thing, a constant dialogue, and that finished imaginative work and projects should arise naturally from this much larger body of rough ideas. Similarly, skill used in these same works should come from a strong foundation of daily drawing, also shown in the sketchbook. Real finished works are the fruits of the artist, but the tree from whence they come is the sketchbook. This is the heart of the artists life. This aside, real sketchbooks are also just so much fun, I like to look at an artists sketchbook more than their actually work! Sketches almost universally have more freedom and vitality, as well as humor and wild ideas.
Making the transition then to working on digital artwork was a stroke for me, as I started out, I used photoshop mainly to color pencil drawings, many directly from my sketchbook. Later, as I became more comfortable working with a wacom, I found it a lot easier to do my sketches in photoshop as well, where was the place of the sketchbook in working this way?
My general process at this point was to open a file, in the size and resolution of the project at hand, and start sketching, saving all the rough work and any random doodles done along the way as separate layers. Would I, or anyone ever see them again? doubtful. Could I ever find a particular one? Again, doubtful. I tried to combat this by doing as much conceptual work in my sketchbook as possible, but utility and speed is a hard foe to fight, and I still ended up with many interesting sketches sandwiched invisibly into countless unrelated files, my sketchbook became thinner, and a great deal of my thought process was lost to myself and the world.
Then one day, not so long ago, I had an excellent idea, what if I changed my digital process to mirror my actual one? What if all my digital work also came from one centralized place? thus the pssketchbook or (psketchbook) was born! I started a file where I began to do all my conceptual work and sketches, every project was begun there, and sketches exported and enlarged to do finished pieces. The file was low-resolution, and small, so I could effectively have a million layers without slowing it down, or making it unwieldy, I had several pleasantly toned background colors, and because of the rough nature of the work, the resolution was not a problem. Now I had all my thought process in one place again, laid out organically and chronologically! Another great bonus is that I now had all my digital sketches in one format, so assembling them into a printed book or putting them online would be far easier than before, I can't hardly imagine the arduous process searching for, extracting, and re-formatting all those other sketches would have been. Nearly impossible. Now my heart is at ease, and as a bonus I have a wonderful object that can be easily reproduced, browsed, and traded with friends! Even my paper sketchbook can't do that!
None of this changes my faith in a real paper sketchbook however, and most of my drawing still goes on there, but I am certainly glad to have saved so much from the dark vaults of my hard drive.