What to wear to my first Jiu Jitsu class? image
At first, If you are trying it out... before  you purchase a uniform of your liking, You need to come in regular sports wear, such as Shorts and T-shirts or rashguard or Jogging pants. You must feel comfortable and at ease for the training.

Then, If you Like BJJ, you will need to get the proper uniform:

The kimono aka Gi is the Martial Artist's Tool
You usually don't need to own a Brazilian Jiu-Jitsu Gi for your first class. T-shirts, board shorts and sweat pants are all fine. Sometimes you can wear a Gi or uniform from another martial art (ask the instructor about this issue).  You will need to buy a Brazilian Jiu-Jitsu Gi if you continue training.