In my first school, another new teacher and I inherited back rooms stuffed with 25 years of dissection specimens that were older than my students,  random chemicals, unmarked bottles, etc. We were woefully unprepared to clean out the closet and set up a safe chemical storage area.

If you are in a similar situation, the Lab Safety Institute is offering a free chemical hygiene plan for schools that you can use as is or adjust to your situation. They also offer safety training (elementary and secondary courses) with teacher scholarships available.