Wear comfortable, non restrictive clothing that allows for breath and movement - yoga pants which cover the legs and show the knees, and a yoga top that allows for inversions - turning upside down - are highly recommended. Be prepared to work barefoot.
Come lightly hydrated and bring a bottle of water for after practice.
The practice of yoga dislodges toxins from your cells and drinking water will help flush these out of your body.
Blake has mats and props available for everyone's use. Be aware that mats are not washed in between use and so your own mat may be preferred for hygienic reasons.