Focus
One of the biggest challenges with telecommuting is maintaining focus. Distractions are everywhere, and they crave attention. The most obvious culprit is The Internet (insert scary music here), and I do not think I really need to go into how easy it is to lose a few hours mindlessly clicking through the ether. But it is easy to overlook so many other things that can pull away focus, as well. A TV, stereo, pet, child, roommate, spouse - even some nagging chore that you have been putting off for a week. When faced with a looming deadline at work, that pile of ironing might start to look enticing. It also may be tempting for a housemate (of any kind) to request an errand, "since you're home anyway."
I cannot write away a person's behavior tendencies or lack of discipline. But by taking a step back and sizing up anything that could interfere with the productivity of a home office, the act of recognizing distractions before they occur will translate into successful telework. This not only requires elements of inner discipline, but the ability to communicate that discipline to other people who might affect your productivity as well.
A recurring theme here has been creating an environment in which there is ideally no difference between a "real" office and a home office, with regards to the ability to perform the work that is expected. Sure, the company office might have a kitchen, break room, cafeteria, or gym - and hopping up a few times during the workday is necessary and essential. The same is true for telecommuting. One cannot be expected to be chained to their desk for 8 hours, so my point is not to say that eating lunch and catching a rerun of Seinfeld will cost someone their job. But it is simply too easy to fall into a pattern of turning away from the work at hand, thereby losing the trust of one's team or, worse, manager.
(Incidentally, I should point out that it has taken me nearly eleven months to write up this simple guide and publish it to a rudimentary web site. As tempting as was to work on effectivetelecommuting.com during work hours, I promised myself I would practice what I preached.)