Agreed on the above points WS,
plus treat your office like an office, take a tea break away from the office area, structure your time, if people call TELL THEM RIGHT OUT that you are working, or else they will suck your time away. People turn up at our place and Tracey says i am working, after a few minutes they ask, is he coming in then? she says 'he is working' they wouldn't dream at turning up at your office so why should they at home. Often i do call in for about a minute or so when they arrive to welcome them, then i say I have work to do now see you again, and off i trot.
controlling visitors is one of the big problems.
Start at a set time and structure your day.
Working from home will allow you flexibility (if there is a big game on tv then you can watch it, but will have to cover the time) NEVER do this on the fly as it will creep up on you as a bad habit, always plan ahead and arrange to work the time after your normal hours, this way you feel good in yourself , it gives discipline (which is the KEY word in working at home) and it will let all around you know what to expect and when.
Oh and get loads and loads of cakes and biscuits in and buy a cycle or a rowing machine to burn off the calories taken in from biscuit and cake eating