>I'm interested to hear stories from consultants about when they realized the time was right to go out on their own. What were the major factors in your decision? What would you have done differently? How did you approach it?

Besides obvious personal skills and attitude issues, already highlighted in other messages, you should also look at economic issues. I started my consulting journey when I saw that my wife income/benefits would be enough to support our family in bad case. You may also look at general economic situation, i.e. you should understand clearly that software jobs, including consulting assignments, will become rarer in near and, probably, mid-term.