Before my year-ish long hiatus from arting, I barely did any painting that wasn't on the computer. I have a program called Painter (which is, by now, upgraded wayyyy past my version) that I use (or used to) in conjunction with my tablet, which is the 2001 version of this tablet. I highly recommend them. It's never broken, and the only part that's worn out and needed replacing thus far is the plastic pen nib.
I used to get a project in mind and would sketch it out, sometimes leaving it really rough and sometimes almost a finished piece itself, before scanning it to Painter. The sketch scan I use as a background to paint on. Painter allows for different layers, so I just keep painting on top.
In Painter I'm almost always using the round camelhair brush and water blender... I vary the size and that's pretty much it. At some point if I get back into digital painting I'd like to get more adventurous with the brushes. I know I'm missing out.
I usually paint the background first, because I like to have the brush "pick up" colour when I work on the foreground stuff. I find that tying the disparate elements of a digital piece together can be more difficult just because it's so easy to put them in without affecting anything else. Having all my paint strokes affect the layers underneath helps with that, I think.
The bonus with digital art is that it's faster, by far, and no clean-up afterwards.
On the other side of the coin, though, I find I miss out on the visceral feel of getting my fingers dirty. :) Plus, it's reeeeally easy for me to get distracted by details to the point where I lose sight of the piece as a whole. Usually I'll get rid of it at that point, sadly. I have a whole folder on my one drive that's just unfinished .psd files. It's a very sad folder! I try to avoid it.
I do like the feeling of accomplishment I get from one of these big projects; bringing an idea from conception to life, so to speak.
Maybe once I'm past the new and passionate part of my love affair with books, book-making and stream-of-consciousness art I'll get back to planned and ambitious pieces.