Helmets & Racewear
You don't need to spend a fortune to be properly kitted out on track. This collection covers the essentials. The most basic requirement for trackdays is a helmet. You'll need a closed face helmet if you're in an open top car. If you're in a car with a roof then an open face helmet will be fine and can help to keep you cool.
Gloves & boots are also something worth considering, not essential but can certainly make a difference to your comfort and safety.