Fewer, larger pieces — not more, smaller ones
The instinct in a compact flat is to choose small furniture. It usually backfires: several small pieces create more edges and gaps, and the eye reads clutter rather than space.
One properly sized sofa reads calmer than a small sofa plus two chairs plus a side table. Fewer visual interruptions, more apparent room.
Take storage to the ceiling
The most reliable gain in a small flat is vertical. Wardrobes and storage that stop at seven feet leave a dead band above and draw a horizontal line that cuts the room's height.
Running storage to the ceiling adds genuinely usable volume for seasonal items and makes the wall read as one plane rather than a stack of objects. It is also the single change that most reduces floor clutter — the real enemy of perceived space.
Keep the floor visible
Visible floor equals perceived space. Wall-mounted or leg-raised furniture lets the floor run underneath and continue visually to the wall. A floating TV unit and a sofa on slim legs will make a room feel materially larger than the same furniture sitting flush to the ground.
Light: layer it, don't centre it
A single ceiling light in the middle of a room flattens it and pushes the corners into shadow, which makes the room read smaller. Layering — ambient, task and accent — lets the eye find the boundaries.
Lighting the corners matters most. A wall light or floor lamp in a corner tells the eye where the room actually ends. Under-cabinet lighting in the kitchen does the same for the worktop.
Colour, honestly
Light colours reflect more light and generally help, but "paint everything white" is lazy advice. A completely flat white room has no depth cues and can feel like a box.
Keep the large surfaces light and low-contrast, then let one wall or a set of textiles carry depth. Where a wall meets the ceiling in the same tone, the boundary softens and the ceiling reads higher.
Mirrors — useful, and easy to overdo
A mirror placed opposite or perpendicular to a window bounces daylight deeper into the room and genuinely helps. A mirror on a wall facing clutter simply doubles the clutter. Place them for the light, not for the wall that happens to be empty.
What we would do first
If the budget only stretches to two changes: take the storage to the ceiling, and get the lighting off the single central point. Those two do more for a compact flat than any amount of furniture replacement.