The best cosy living room ideas are not really about decorating. They are about accepting that from about now until March, the living room stops being one room among several and quietly becomes the whole house.

It happens quickly up here. In mid-September the light is gone by about eight; once the clocks go back on Sunday 25 October it is dark before five, and the sitting room takes on all the work the garden and the kitchen table were doing in July. So it is worth setting it up properly, and none of it costs much thought.

Start with the light, not the furniture

If you change one thing this autumn, change how the room is lit. A single bright bulb in the middle of the ceiling flattens everything beneath it and makes a room feel like a corridor at six in the evening. It is the most common reason a perfectly nice living room refuses to feel warm.

The fix is to light at three heights. Something low — a lamp on a lamp table beside the sofa, shade at roughly eye level when you are sitting down, so around 100 to 110cm from the floor. Something mid — a lamp on a sideboard or a bookcase shelf across the room, so the far wall is not left in the dark. And something tall, or a second low pool of light in the opposite corner.

Three modest pools of warm light will do more for a room than any amount of new furniture. Put them on separate switches if you can, so the overhead light becomes the thing you use for hoovering rather than the thing you live under.

Three lamps and a throw will change a room faster than a new sofa will.

Somewhere to properly sink into

Cosiness is partly a question of posture. A sofa you perch on is a sofa nobody stays on for a whole evening, and the measurement that decides it is seat depth.

Most sofas sit around 55 to 60cm deep, which is right for sitting upright. If you want to curl up with your legs tucked under you, look for 60cm or more, and try it before you buy — depth that suits someone tall can leave a shorter person perched on the front edge with no back support at all. Our guide on how to choose a sofa covers the rest of the fit.

Beyond that it is a straight choice between two kinds of comfort. A recliner is for one person settling in properly for the evening, feet up, and it is the piece customers come back and thank us for in January. A corner sofa is for a household: it lets four people sit round a stove without anyone facing a wall, and the chaise end is the most argued-over seat in most houses.

Layer the texture against the oak

Solid oak is warm in colour but hard to the touch, and a room of nothing but timber can read as handsome rather than comfortable. What softens it is texture, and autumn is when you add it.

Wool throws over the arm of the sofa, a couple of heavier cushions than you would want in July, and a rug with some pile underfoot — which matters more than it sounds in an older stone house with a cold floor. A few things worth knowing:

• A rug should be at least as wide as the sofa, with the front legs standing on it. A rug that floats in the middle of the floor makes the room look smaller, not cosier.
• Mix the weaves rather than matching them. A chunky knit, a flat wool and a smooth cotton in the same colour family will always look better than three identical cushions.
• Keep a throw where you actually sit, not folded decoratively where nobody reaches it.

Our decor range is the cheapest way to change how a room feels in October, and the easiest to change back in April.

Why warm wood does the heavy lifting

There is a reason oak turns up in every picture of a room you would want to sit in. Warm timber reflects light with a little of its own colour in it, so lamplight bouncing off an oak sideboard comes back softer and more golden than the same light off a white-painted unit or a glass table top.

Glass and high-gloss surfaces do the opposite: they throw back a hard, bright point of light, which is exactly the quality you are trying to get away from at this time of year. If you are choosing between finishes for a piece that will live in lamplight six months a year, that is worth weighing. Our piece on why solid oak outlasts flat-pack makes the longer case for the material.

A calm room is a cosy room

This is the part people skip. It is very hard for a room to feel restful when every surface has something on it, and the living room accumulates faster than any other: chargers, remotes, post, school things, the paperback someone abandoned.

A sideboard takes most of it and gives you a surface to put a lamp on. Drawer and basket units take the small awkward things that have no natural home. If your lounge is tight on floor space, our small living room ideas cover how to get storage in without crowding the room.

None of this is about minimalism. It is about the difference between a room you tidy and a room that has somewhere for things to go, which is the difference between clearing up taking two minutes and taking twenty.

The test is simple: can you clear the room in two minutes before you sit down? If the answer is yes, you will actually sit down.

Arranging seating round a stove or fire

A wood-burner is the best thing a Highland sitting room can have and the easiest thing to arrange badly. Three principles get it right.