A home darkroom is really two different problems: fragile optical equipment like the enlarger, and chemicals that many municipalities legally classify as hazardous waste. Handling the chemicals correctly comes first, since that part has rules, not just best practices.
Pro tip: Many camera stores and community darkrooms will take working chemistry off your hands rather than you disposing of it, which is often the easiest option for a move.
Watch out: Never pour used photographic fixer down a drain; it contains dissolved silver and is treated as hazardous waste in many areas, with real fines for improper disposal.