You can do this without debt. it's been done countless times. BUT you need to put in some of your own money, versus borrowing. Don't create your own personal debt. I doubled up-work two jobs at once. Focus on very high margin revenues. You can find these.
Consider having a partner. You've got to have a differentiate yourself at least to get in the door, otherwise it will be VERY difficult to unseat current service providers. Get assignments from your network first. All outside your network will ask "Who are your current clients". Beyond your network target smaller, early stage companies.
Don't compete on price, you'll go out of business fast. Compete on unique services. Sniff out prospects who just want your proposals for your expertise with no intention of retaining you.
Create a well thought out business plan and bounce it off as many experts as you can. This input is critical in sharpening your plan before expending your time and effort.
Once have this GO! be relentless. The difference between entrepreneurs is passion, creativity, being able to think from a blank sheet of paper, and picking yourself up when you get knocked down.
Take risks. I always remind myself of Tim Cruise in Risky Business when he brings the prostitutes into his parents home while they are away to make money. The person from Princeton comes into the party for his interview and says to tom "Your just not Princeton material" Tom feels the bulge of cash in hos pockets, puts his shades on and replies "You know, everyone and while you just have to say, What the F^&*ck" He goes on to make a lot of money and also get into Princeton. (He creatively took care of his interviewer)