Post your system's performance. (or PM me)
The performance, the measures you use and how you present the report should be more than enough to assess how well you are as a system developer.
Also, what would help is the type of environment you require for the models. eg. Max commish, network and computer stuff (like requiring a remote server to be setup)
We can start there.
I used to be in a few partnership in Chicago, developing models and trading for funds and firms, so hopefully I can provide you with a few tips...
One important aspect of being a freelance developer is how you present your project. And keeping the presentation well thought out beyond the scope of the system itself.
Next aspect is the contract and protecting your assets. Things like source code, monitoring / support, monetary aspects need to be well thought out.
Finally, network. As you know, one successful deal leads to providing yourself with a name, leading from one to another. It's a small industry, especially in Chicago. The toughest deal is the first one and the most important. Some projects I've done has not made money but I kept the losses small and very professional. I personally stopped a system in a very short time, after I realized that the system will not perform. That in itself lead to a next deal with the same firm, purely because I took the loss professionally.
Again. Small industry. Gotta keep all the bases covered before you step into an office or you'll get burned.