In case you haven't already thought of them, may I suggest (1) an aid to photography, and (2) an aid to easily showing measurements:
(1) PHOTOGRAPHY AID
Investing in a "tri-fold foam presentation board" (cheapest I've just browsed are about £11, available in various colours incl. all-white and all-black) would:
(a) make taking photos easier as regards lighting and avoiding reflections through windows or from artificial lighting.
(b) hide background clutter; even if your stuff in the background is neatly organised, buyers really only want to see the item that's for sale.
I say "tri-fold" as being foldable they're easier to store.
(2) EASY AID TO SHOWING MEASUREMENTS
Also, depending on the item, a universally recognised scale object's helpful e.g. a pound coin, or a ruler next to the item.
Depending on your item's size, maybe consider buying a crafting mat aka cutting mat? They range from dirt-cheap to expensive; usual size is A3 but you can buy A2; or even A1 (they'll be foldable). They're covered with printed measurements: often one side's covered with centimetre squares with inch squares on the other. Most have centimetres labelled along one axis and inches labelled along the other. Some mats also have angles printed on them and often life-size useful sizes that get frequently used like A5.
It's taken almost for granted by crafter-buyers that crafter-sellers photograph an item on their mat so that you can immediately gauge the item's size. If you use such a mat routinely, you probably don't need to worry whereabouts on the mat you place your item.