Furniture has more shape than a flat floor plan suggests. Sofa arms, chair backs and cabinet corners all use up material. Give yourself space to position a plastic dust sheet without pulling it tight over the first corner you reach.
Prepare the item
Remove loose cushions, ornaments and other small items where practical. Keep them somewhere outside the work area. Check for anything pointed or rough that could catch the sheet, and make sure the surface is ready to be covered.
If the item can be moved safely, leave a workable gap between it and the wall being decorated. That gap lets you paint without continually leaning on or adjusting the cover.
Unfold, then position
Open the sheet in a clear space. Find the centre and lower it over the item with the clean side facing the furniture. For a broad sofa or dining table, another pair of hands makes it easier to avoid dragging one edge across the floor.
Let the sheet settle before making small adjustments. Keep enough slack to follow the furniture's shape. A taut cover can pull away at the opposite side when it is nudged.
Walk around the item and check from several angles. Look at arm ends, back corners and the side nearest your work. When two sheets are needed, inspect the join rather than assuming an overlap will stay in place throughout the job.
Check during the work
Keep tools, paint containers and sharp objects off the cover. If you need access to the furniture, stop the messy work before lifting the sheet. Return it carefully and check the edges again.
At the end, bring the outer edges inward so the marked side stays inside the fold. Avoid shaking the cover over the item you have just protected. Inspect both the furniture and the sheet before deciding what can be stored or reused.