I've noticed a few comments from people who actually did overcome their fears to start a business, but struggled to be profitable. From talking to many consultants/freelanceres, the biggest causes for struggling with your business profitability are:
--not charging enough
--not creating marketing pipelines, thus struggling to get consistent work

To be able to charge more, you'll typically need to be in a more specialized niche. For example, doctors who have a specialty--gastroenterologists, for example--are able to charge a lot more than a general practitioner. The key is knowing how to research and identify a profitable niche. A couple other benefits of being in a specialized niche are that it's easier to stand out, you'll have less competition, and clients often come to you instead of you having to market to them.

To create marketing pipelines, you'll need to identify where your prospective clients are, and create a presence in those channels, establishing yourself as an expert who can solve their problems. The wonderful thing about marketing pipelines is that they automate your marketing, so you no longer have to spend as much effort on it. I haven't made a cold call in probably 2 years; instead, new prospects seek me out, and I follow up on warm leads who already know that I'm an expert. It makes it a ton easier to maintain a consistent and growing workload--that's how I've been able to consistently grow my revenue by over 30% annually over the past 5 years--even during the global economic meltdown--and actually work LESS than I did at my day job.