Ask them who else you should talk to. You might want to record them saying their names and what they do. Record sounds from various distances and perspectives. For example, a toilet flush is very different recorded from five feet away than it is with the mic resting on the plumbing. You can't record too much.
Tape is cheap.
Collect and catalog sound effects and ambiences. Save everything, including your notes. Pop out the safety tabs in your cassettes after you've recorded, so you can't accidentally erase them. Never throw away a master. Make safety copies of precious stuff.