Start by noticing where your eye naturally goes when you enter the room. Often, the wall behind the main piece of furniture – like the headboard in a bedroom or the sofa in a living room – makes the most sense as a feature wall. Another good candidate is the wall you see directly opposite the entrance, since it gets attention first.
Avoid very broken-up walls with lots of doors, windows or cupboards. Feature walls work best when they have enough uninterrupted area for colour, art or texture to really show. Also think about how you use the room. In a bedroom, the wall behind the bed is almost always the most logical choice; in a dining room, it might be the wall behind the table.
Once you pick it, the “feature” doesn’t have to be wild. A richer paint colour, subtle wallpaper, wood panelling, or a strong art arrangement can all do the job without overwhelming the room.