We have a 6m x 6m with double sliding doors.
Our old kitchen makes the cupboards on the left - awesome storage. We have some old metal supermarket shelving (no upright bars at the front, so is great for big items) along the back which is super-strong and heavy duty - bought from the back of a hardware store for $50 when old Charlie Carters closed down. And a home made mega-bench. In the ceiling we have long term storage for eskies, swags, tables, jerry cans etc. We collected some bunk bed bases from the roadside "bring out your dead" council collection and hung them from the roof trusses - they make great light weight storage shelves.
We even have an old fan hung from the ceiling and a whirlybird in the roof for good ventilation. This shed is the home of many successful home handyman jobs