Having been a photographer hobbyist, freelancer, semi-professional and professional over the span of 40 years, I've come to confront a few realities. I began my business underfunded in terms of cash and productive time.
1. It is investment in marketing and sales that matter overwhelmingly in the business, and that must have a 3 year minimum to succeed; thus cash or credit reserve must be 3 years operating costs including outside sales and marketing. In the case of a small studio trying for the high end of the spectrum ($2000-$8000 sale) that means planning for a studio that costs $2500 per month to operate is $100k for 3 yrs, the staffing, sales/marketing, creatives, web marketing, PR, exhibition costs, etc. would be approximately $325k per year, so $975k for 3 years should have been my minimum investment.
2. While being completely solo has its advantages, solo whilst being full time employed elsewhere has huge disadvantages; you can't meet new prospects while you are presenting to a room full of IT people. Being engaged with a busy IT department doing big things keeps the living expenses paid at the expense of my most productive window of time on a daily basis (for me, 7-noon). Organizing and selling a portrait session after a 10 hour day of IT is tough. Really tough if you aren't a natural sales person. And then, there's the actual photography, the thing I love to do...also done after an often grueling day.
Despite the shortcomings of cash and time, I still took a stab at it again, and have lost it all.
What have I learned? People with money can make money, and the rest of us work for them. I just need one good lotto hit.