I worked as a freelance engineer for some years. It can be a way to go broke, slowly. All of my work was word of mouth or existing customers who knew my work, so I didn't have to worry about bidding, but it's still a feast or famine business. Never used any kind of service. Around the time the economy soured and projects dried up (around 20 years ago), one of my customers offered me a full time job and I accepted it. But the flexibility of freelancing was good for awhile. As far as needing a PE license, technically, yes, but it's not enforced and very few have a license. If you were designing bridges or such it would be more important. Rather than holding out as an "engineer", I offered "design, drafting, and CAD services." The other problem is you're competing against every recent graduate living with his parents and running a pirate or student copy of CAD software part time in the evenings. They can't do the quality of work that an experienced engineer can, of course, which is why reputation and word of mouth is the way to get decent jobs.