Name the outcome, not the topic. "A session on discounts" produces a tour of the discounts page. "Agree our peak-season discount rules and who sets each one up" produces a workshop. Put the decision you need in the first line of your brief.
Ask for the agenda and pre-work list before you agree a price. A facilitator who plans properly wants access, a sample of your data and attendees' questions in advance. One who quotes a full day without asking anything is selling a session they've already given elsewhere.
Check they can facilitate, not just present. Knowing Shopify well and running a room well are different skills. Ask how they handle a team that disagrees, how they keep quieter people involved, and what they do when an exercise breaks on a shared screen.
Ask what attendees will do with their hands. Hands-on time in the admin or a duplicate theme is what separates a workshop from a talk. If the agenda is mostly slides, book a webinar instead and pay less.
Sort out access a week before, not on the morning. A facilitator who is a Shopify Partner can request collaborator access using the 4-digit code from your admin, and the access starts once you approve the request. If nobody uses it for 90 days it lapses, so a session booked months ahead may need a fresh request. POS is out of reach for collaborator accounts, so retail-floor sessions run on your own devices with staff PINs.
Plan around the size of the provider. All three workshop leaders listed here work as freelancers. For a multi-day programme or several teams at once, ask who co-facilitates and who covers if the lead falls ill.
Walk away from promises about revenue, an app recommendation in every exercise, and an agenda with no follow-up plan after the day.