If you are going to be a true freelanceer (design through a third party) then you need to establish a policy of copyright, contracts and process.
Freelancing is a sticky situation when it comes to showing of your work. If a sign company hires you to design something for thier company, then they usually want to have all the rights..where does that leave your portfolio, there needs to be a balance of shared promotional rights...or you have to get paid more for handing over all rights....without a portfolio, how can you market yourself? You need to develope a contract that spells it all out so there is no second guessing when problems arise.
The other thing is process. It's hard enough designing for a real customer...try adding the filter of a sign shop who is relaying that information. Hourly makes more sense since you should not be held responsible for someone translating the job wrong. I use a creative brief that takes a lot of the guessing away.
Since freelancing is wholesale design work, you might want to think about a site for freelancing and one for your design shop. You dont want a client stumbling into your wholesale part asking why they don't get that break.
A good book is "Talent is not Enough: Business Secrets for Designers" by Shel Perkins.
The bulk of my work is freelance where I have no rights of promotion...not that I care to much since it's mostly code signage and not much to it. I charge enough for that inconvenience, you need to get a balance of paying customers and freelance to keep the portfolio updated.
Gino brings up a great point on showing work you did at another company. I think every freelancer has had to do that at one point, but it's something you need to stay away from or replace that work with something from your company as soon as possible. Stating in your resume is fine though. If you do not have "real" work you can show. Make it up. You are showing your talents...made up work is a demonstration of that talent you are trying to sell, then you can replace it with real work as work comes in.
