I've been working on some big poem illustrations. When I started one of a big English garden, I thought maybe if I go back to good old-fashioned drawing with real pencil, this will go faster. I got as far as drawing the big violet when I realized that was a dumb idea. It was messier, it was going to take extra time to scan everything, piece it all together, deal with the multiple layers, clean it up, etc. etc. So I went back to my tried and true Photoshop brushes.
A good tip: use the bracket keys [ ] to increase/decrease brush size. Also, you can right+click on the screen for the brush palette to pop up. Both efficient space saving tips I never use because I am stuck in my ways.
And finally, a cool little trick with Paths if you are drawing straight lines.