Once you’ve been to a few events, practices or meetings and decided that the SCA is for you, one of the next things you’ll want to do is figure out your period persona.
The SCA is all about learning by doing and the easiest way to do this is to step out of your modern "persona" (who you are and what you do in real life) and find the "you" that might have existed in the Middle Ages.
To make the point that "now I am my medieval self", people usually choose a new name and make up a plausible story about who they are and when and where they're from. This is especially helpful for those who have obviously-modern names. However, it can cause a lot of confusion for newcomers to the SCA, since just about everyone has two names!
An extra word on names in the SCA: Note that the term "usually" in the paragraph above is bolded. Choosing a new name to differentiate your medieval and modern selves is entirely a personal decision; some people never do, choosing to use their real names for both, and some don't choose an SCA name until they've been in the Society for a while and have decided on a time period and place for their persona (which will probably have a bearing on the choice of name). The decision is entirely yours to make. If you are interested in pursuing the name and persona process, please have a look at these pages:
Your Persona can be as simple or as complex as you wish! Here are some questions that may get your creative juices flowing in developing your persona; but remember that it doesn't have to include all of these!
Why Does Everyone Have Weird Names?
More to think about when choosing a persona, from the Ealdormere website.
Tempus' Little Heraldry Book
An excellent primer on choosing an SCA name and armorial device.
The SCA Main Heraldry Page
Many people choose an SCA name for common use and don't formally register it with the SCA College of Heralds. This is perfectly OK, but if you think you ever might want to "make it official", it's a good idea to do a little reading here first on what's registerable and what's not. That way, you won't be disappointed down the road when you find out that the name you've been using for several years (and by which many people now know you!) can't be formally registered. Of particular interest are the SCA College of Arms page with the Rules for Submissions and the Heraldic Primer.