also have uploaded a photo of our piano and mirror which I love. and I photo of our dining room light which I would also like to keep there.

I would continue with frosted glass like the door on all the windows because the view of the other house. Not sure where you live, but you can get a frosted window film that you install yourself. In bedrooms and lounge, depending on your style, you might like a woven roman shade with silk drapes.

Clear any shrubs / trees / weeds, away from around the house - not saying go out with a chainsaw and slash everything down to the ground but make sure there is nothing higher than the window frames directly around the house or even leaning on the house. Taller tree's may be able to be pruned to allow more light through e.g. lift the bottom of the growth up higher by removing lower branches or thin out branches from within the canopy. Bring in as much sun as you can during the day. If you are planting a new garden, always look at the height of the tree's when they mature and if possible mix some trees that lose their leaves in winter so you obtain maximum sun. Check your insulation e.g. last year I added a new layer of insulation onto of my existing ceiling insulation. If you have dampness under your house maybe look at channelling water away from the house with what ever means you can afford e.g. professional drains right around the house or just dig trenches. You may wish / need to add black plastic over any clay / ground under your house if you are not on a flat concrete block based house. Open curtains during the day. Dress to the conditions. If you can't afford to heat the entire house just heat the room(s) you are using but make sure the non heated rooms get ventilation from time to time (especially lovely sunny days). Pile the blankets on the bed and even use a blanket over your legs if you are sitting watching TV or working on your computer. Think SUN SUN SUN. If you are renting and the house you are in gets very little sun, now is the time to start looking for something that gets more sun. Winter is the best time to look.

You are correct the place does and always will look a bit sparse when you only have blinds. The question with curtains is sometimes dependant on what climate you live in and I am not sure where you are so I am going to say. If you need curtains for heat go for a quality curtain to the floor with a fabric that is not stiff (as I discovered I now own after buying curtains off line for my spare rooms). The expensive curtains I brought for my living room have a softer texture and hang so much nicer. As I need Curtains / Roman blinds for heat I have backing fabric etc on the expensive made to measure ones, where as the cheaper ones are just thermals. If you only want to add a curtain for looks and do not require it for heat I would recommend going with a lovely sheer / half see through fabric that drapes really well, this will add a point of interest and you can colour match or add a loved colour to a bare - white on white - cream on cream - colour scheme.