Here's a great interview with a Heavy Equipment Operator:

Any advice for those seeking a career as a Heavy Equipment Operator?

Start out at the bottom, learn to check grade for operators and laboring. Watch closely what the veteran operators do, I learned most of what I know just from watching. Be prepared for long hours, long periods of isolation from others, extreme heat and dust in the summers and the joy of zero degree temperatures in the winter; it is definitely not for everyone.

Career as a Heavy Equipment Operator