How would you make your house feel cozy besides using pillows and books?

Sitting areas (two chairs, one table), area rugs in bright colors to match your pillows. Lamps and candles help a lot, and fresh flowers, throws on the back of chairs or couches.

All black inside? Like from smoke? You can use wall hangings out of some cheaper cloth that you can wash or change out once or twice a year, it would really brighten that up and make it cozy.

Or, don’t laugh at me now, you can wrap the cloth around cardboard boxes of different sizes and do the whole room in a nice pattern, with silky materials or something.

If you don’t use the fireplace fill it with silk flowers.

Here are some ideas for the fireplace.

I love area rugs for bare floors

This

You GOTTA look at it!

Candles and maybe some chenille throws tossed casually on arms of the couch, edge of the bed, etc.

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Repaint. Change your lighting. Add or change curtains. Are your chairs and tables made of wood? If not, make it so. Add some natural touches – stones, branches, cones, leaves, shells.

Thanks everyone. I can see I need to re-paint and add flowers. Plus, we have no curtains. Only wood blinds. That might have a lot to do with it.
I guess I thought you dont put out flowers in winter.
Non-smoking household. The fireplace is black from the natural gas fumes.

Less light means brighter colors need using. Well placed mirrors in confined spaces can be used to reflect light to different areas as an alternate means to light in the day, candles for the night. There are heaps of lovely tea-light holders out there on the market, some with coloured glass some with just clear holders. Chuck out those wood blinds, because they’ll be absolutely hopeless in letting in light. Get some curtain holders, if privacy is a huge thing, then obviously get some net curtains that aren’t too heavy in design – not thick on the borders with twiddly bits that look fancy, just plain thin net curtains.
@KNOWITALL‘s idea with covering boxes with silky materials or something is a good one (because I’ve been doing that for years!). Good fabric is easy to get hold of if you know where to get it – I was fortunate enough to locate a local fabric store and it didn’t cost a great deal to get a few meters of good quality, decorated fabric. I’ve covered an old trunk with it and nobody is any the wiser as to what’s under the fabric.
Flowers can be good but costly. Fake ones are a no-no, not least because they can look terribly fake indeed, but also dust. Those things are a pain in the ass for picking up dust – and depending on the level of complexity in design, even worse for getting the dust off ‘em.
Bright pictures might help, but not too many else small rooms look cluttered.
I dunno what else to chuck in on this one to be honest.

I like lighting, like lamps, pretty ones. All on different levels. Lighting can be a decor on its own. Plus candles.

We use area rugs. One covers 90% of the living room and is beige with coral flowers, the other one is olive green. Both are wool.
I cannot “chuck” the custom made blinds. They are for privacy and very expensive in white. The sheer curtains is a great idea, though.
Yes; the furniture is all wood. And lots of it.
I need to be thinking about the candles suggestion and, with a lot of luck, I’ll have roses this spring. They’ve looked dead for months due to the Texas drought and indeed some did actually die.

Not sure what color your walls are painted, but a light color on walls can do wonders to brighten up a room.

When I moved into my house, there was dark paneling on the walls, and dark, slate-looking vinyl tiles on the dining room and kitchen floors. I painted the paneling a color called “Country White” and had light colored flooring installed, and it was like a miracle, as far as making it look like a different house.

The living/dining rooms have some sort of sponge paint. I don’t know what it is. And the walls are not smooth in there, either. They’re pale beige and cream colored and have texture.

@Aster: Do you like the sponge paint? From houses I’ve seen, unless it was done by someone really talented who really knows what they’re doing, it usually looks like crap (i.e. amateur hour).

I do like it. But you might mean the gaudy kind. Mine is off white with light tan and is extremely soft and I had to go look to see if it had those “orange peel” indentations and it does. It looks like they took paint roller and broke off some of the foam or whatever those us so it isnt a smooth surface. It looks a lot like it’s just painted in pale beige.