Provide a sound, level base and anyone will be able to erect a garden shed - though an extra pair of hands is essential for lifting the panels into place.
Have a steady pair of stepladders for working on the roof - and get someone to help you lift the heavy wall and roof components into place.
In the long run, it pays to buy a quality shed which, with routine maintenance, will provide a dry, sound facility for storing tools, materials, garden furniture and other equipment.
Never skimp on the size of shed you buy. Get the largest that will suit your garden - extra space is invaluable as not only can you store more, but the shed will be easier to organise and items will be more accessible.
