Flyers and posters
The places where you can find the best donors are: professional and amateur athletic organizations, such as Olympic and dance, universities (aimed at the best athletes), various sports and athletic centers such as rock climbing, gyms, swimming pools, etc. Main donors: young, healthy and athletic.
You can deliver the brochure directly to potential donors or leave the brochures in the facilities where people can pick them up and take them home.
You can also laminate posters and place them on walls or other public spaces around those areas so potential donors can sign up.