No Free Comps.

Jeffrey Zeldman, as always, writes a great article: Don't Design on Spec. I've been following this advice since starting out on my own. The one time I did near the beginning, I realized what a bad thing it is. I spent a few hours creating a nice design, only to have my bid declined, and a design similar to mine appear on their website. No more free work from me. I do find that the clients that understand why I don't are usually great clients and have more experience working with designers, and they understand your time is valuble.

I'll reprhase a bit. People who request a Design with your bid do not value your time, and may not understand how long it takes. Bad clients. Run away fast.