Steve Friedl, the man behind UnixWiz.net, has an older article on consulting that’s worth reading. I pulled out some of the “maxims” that he writes about that stuck with me:
You must give the customer The Warm Fuzzy Feeling™
For a good consultant, your voice is comforting: Be very easy to find
It’s better to give away some time than to throw away your reputation (I love this one)
Your best advertisement is publishing original, technical content
If you’re booked up solid, your rates are too low
The best way to make a lot of money is to make your customers a lot of money
Every one of these is solid gold advice. I live by a lot of these rules, and I’d say that most succesful consultants, whether they design kitchens or optimize websites are much the same.