For anyone discovering the SCA for the first time in this thread, I strongly encourage you NOT to make the first thing you do one of their weekend events. Events are a time when plenty of stuff is going on and everyone in the Society has the stuff they are interested in, so they'll be doing their stuff and you may or may not have anyone spending time with you figuring out what stuff you like or explaining their stuff to you.

Your best bet is to find out when your nearest group has combat practice (usually held at a local park) or other meetups (often classes or business meetings) and start by attending those. Google "SCA (your city name)" and you'll likely find them. That way, you can make friends and discover your stuff in a compact setting and then when it is time for an event, you are walking in there with people you know and stuff to do. You will also have a much better handle on the customs and jargon of the Society which will make your first event less foreign.

Also be aware, like any social organization, you are entering into a regularly scheduled program already in progress. Some of these people have been participating for decades. There are social cliques, there are subgroups around particular bits of stuff that can be insular. The Society will tell you they are great at welcoming newcomers (and in fact there are newcomer's officers and even awards most regions give out for helping newcomers) but unless you're in a local group that has a very strong newcomer program, the onus to break into these pre-formed social circles is going to be on you. That can be a bit much for the shy, introverted, or anxiety-prone. (Ironically enough, once you're in and installed in the SCA, you're actually in a great place for the socially-challenged as you're surrounded by similar nerds with geeky interests you likely share.)

Source: I was in the Society for over 10 years, including being a corporate officer of the organization. I also literally wrote the article "Getting Ready for Your First Event" that is still used on the SCA Newcomer's Portal which, coincidentally, is a website I also literally designed myself.