What to wear? I think that is one of the first questions every asked in history, and is typically one of the first questions asked by newcomers to the SCA. See you are already participating in the spirit of recreating history!
Period garb is great because you have several centuries of fashion spread across multiple countries to choose from. You can choose to keep it simple or go for a full historical wardrobe that would put a king to shame. For your first event you might be able to borrow garb from your fellow SCA group. But if you would like to get a start on your own collection here are a few directions.
Tunics are a simple design that shows up across many periods in our history. They are fairly easy to make and can be used for nearly every event! Plus they can be mixed and matched with loose pants, skirts, and surcoats to give you a change of pace.
Here is a great article to get a person started on their own garb!
Intro to Garb ~ By Cynthia Virtue aka Cynthia du Pré Argent