Most rooms don't look unfinished because of bad furniture — they look unfinished because the colours don't talk to each other. Here are simple, reliable rules for pairing curtains, bedsheets and cushions.
Your wall is the biggest colour surface in the room, so it sets the rules. Warm walls (beige, terracotta, mustard) pair best with warm textiles; cool walls (grey, blue, sage) pair best with cool textiles.
A simple ratio used by decorators: 60% of the room in a dominant neutral (walls, large furniture), 30% in a secondary colour (curtains, bedsheet), and 10% in an accent colour (cushions, throws). It keeps a room from feeling either boring or chaotic.
Curtains and bedsheets are the hardest and most expensive to change often — safer to keep these in neutral or muted tones. Cushions and throws are inexpensive to swap, so this is where a bold colour or pattern belongs.
Hold the fabrics or samples next to each other in daylight, not under artificial light — indoor lighting can shift how warm or cool a colour looks. If it still works in daylight, it will work in the room.