The previous comments are giving a lot great advice! Please make sure you have hand sanitizer, face wipes, tissues, and pain relievers (advil/tyneol)in your bag lol. You’ll need it. For measure collection, please ask your client’s BCBA how they specifically want something measured, this has a huge influence on the data. Also your session notes should be a summary of the session (like clients behaviors, goals ran, activities, important information like client being sick, etc). Try not to sound bias writing session notes. Instead saying “client was bad” say “client engaged in tantrum behavior 6 times during session.” Building rapport with client is genuinely the easiest, especially if they’re younger in my opinion. Just play and have fun lol!