The first question to ask your self before taking the plunge into the adventure of creating a persona are where, when, who and, sometimes, why? These questions make the base for your research in material culture, first garb, then maybe feastgear, tents and pavilions, shoes, interior textiles, furniture and so on. The adventure might become a lifelong passion for knowledge.
After hanging out with Thora (http://www.morethancod.net/) for a week at Double Wars the thought of why we chose certain periods and regions for our reenactment/personas/geekiness hit me. I started out in the early nineties jumping all over medieval history making a little bit of everything, then decided to focus on the 14th Century, mainly because I live on Gotland and parttake in the Medieval Week that revolves around the battle of Wisby and Gotland in 1361. Anything 14th Century was game back then.
Since a few years I have shifted my focus to late 15th Century German. First out of pure love for mad headgear, the artwork from masters like Albrecht Durer and Master of the Hausbuch, then for the amount of sourcematerial coming from this region. My persona shifted to Renike Tucher, of the Tucher family, burghers from Nuremberg, and I focus on the time-frame 1470-1510. And believe me, I have so far only scraped the surface!
Thora has chosen another path, the one of digging where you stand, and focuses on the local culture of the far North of the entire medieval period in Norway. Fascinating and very much a contrast from mine, in terms of available sources, hardly any artwork but a material culture that would have been very much the same over the centuries.
So, have you decided on a where, when, who and, if so, why?