Garages have a way of becoming the default storage spot for everything that doesn't have another home — old furniture, holiday decorations, tools, boxes that never got unpacked. Before a cleanout, a quick walkthrough to flag anything you specifically want to keep saves time and avoids mix-ups.
It also helps to group similar items together if you're able to — tools in one area, boxes in another — though this isn't required. Even a rough sort makes the actual hauling faster.
From there, it's mostly about access: making sure there's a clear path from the garage to the driveway or street so a crew can move efficiently without navigating around obstacles. The less time spent maneuvering, the faster the whole job goes.