Medical school is no free ticket - that's for sure. For my first two years of medical school, I taught MCAT's at Kaplan. This worked out pretty well -- the pay was good -- starting at about $17/hr -- after teaching a number of classes, I was making $22/hr. The trick was teaching a few classes at a time -- that way, the preparation time for each class is less. Proctoring practice tests on weekends was the true bonus -- it was like getting paid to study while making sure everyone took their test on time. I also picked up a couple of side jobs -- tutoring first year students (some of them my old Kaplan students!) as a second year -- designing web sites. Basically, I just found time to work during those first two years. The clinical years are a little trickier. Evenings and weekends are no longer free territory. I found that I could no longer teach Kaplan, but I could still tutor -- scheduling is easier. No longer raking in the bucks, but still surviving. In the end, I feel that you can work as long as you can manage your time wisely.
good luck,
James