What information do I need before I start?

At minimum: a product name, and your company name — company details are a required field, so you can't create an SDS until you've added at least one under Company. You'll also need the country you're selling in, the language for the document, and the regulation standard that applies (e.g. OSHA/WHMIS for the US/Canada). ExactSDS uses country + regulation together to determine which hazard rules and formatting apply. This is just the start — every section further down has its own required fields you'll need to fill in before you can move on, or before you can Confirm & Publish.