Blankets and pillowcases are low-cost ways to make a room feel more comfortable. The details that matter are size, material and what happens in the wash.
Blankets
Fleece and similar fabrics are light and easy to wash, but they can shed at first. Wash once on its own before using it on a sofa.
Pillowcases
Silk-style cases and cotton cases need different care. Check whether they are machine-washable and whether the zipper is hidden, so it does not catch on anything.