The ProjectGet the project files — for Paint.NET
Creating a firefox persona is pretty straightforward:
In making and testing a persona, I found some important design considerations. For instance, you really want to pay attention to how the upper-right-hand corner looks. It's usually the only part that's readily-visible; especially once you have more than one tab open. The most upper-right 275h x 65w pixels are the real target for the whole thing.
Besides the two images, the other available options are "text color" and "accent color". It's important the text color has sufficient contrast with the background of your images — especially in the header. From a day-to-day usage standpoint, being able to read the titles in your tabs is important.
Real-world testing of the persona is important and revealing. 'Busy' graphics might be initially appealing, but they end up just being distracting when used for more than an hour or so. A persona that doesn't distract from browsing is more likely to be retained, so don't go overboard.
Text in the header image is also inadvisable. The header is the background to the tabs, so text will likely under-lap the tabs and look ever busier than ornate graphics.
A new trend in personas is to have animated images. Don't do this.
I ended up starting with a gray gradient and putting graphics on top. This seems to work across platforms and avoids pitfalls relating to distraction and eye strain. The background can be found in the project files above.
I hope you find these observations useful. If you make a firefox persona using these tips, link to it in the comments!