Write up a kind of conversation you would have with a client at your practicum (or desired future practicum) during an initial session to explain confidentiality and its limits.
Tailor the conversation to be age and setting appropriate. Please make sure that you discuss mandated reporting and confidentiality. There are limits to confidentiality and these should be addressed. The goal is to develop this skill that you can use in your client interactions. The more you practice your professional introduction and discussing these policies, the easier and clearer it gets.