how can i practice first aid?

I am with a voluntary organisation, which is where i got my first aid cert (OFA), the organisation works at social events like music festivals football matches and festivals, doing first aid in case its needed. any way the organisation had an exercise and with first aid scenario in it a very bad accidents at a quarry, it was very hard and i am not happy with my performance so i want to get better at first aid because there's no point in me volunteering with the organisation if i cant really help out. so i want to practice more often i have the manual form the course and an accident report form but no first aid supplies so i will be getting more supplies soon and i can get people to act out injuries and i can work on them and mix it up and swap up injuries, anyway how should i practice my first aid.