Waitlisted in UCR and USF

Hi everyone, I was recently wait listed in UCR and USF. I’m hearing that I should be sending them letters while being waitlisted to show my interest. Is that what I should be doing? and if so how should I approach them?

Also, please let me know the chances of being accepted after being put on the wait list for each school.

Thanks so much!

UCR freshman waitlist FAQ:
http://resources.ucr.edu/myucrhelp/PDF/Freshman%20Waitlist%20FAQs.pdf