Another one to extol the virtues of daily airing with open windows. It is the single biggest difference you can make.
I sleep with the bedroom window open on all but the very coldest nights, the bathroom window is opened with every shower /bath and I encourage others to open it when using the loo (which are cleaned daily - as is the kitchen sink).
As soon as we get the first signs of spring then the back door is opened daily, too, for at least a couple of hours and at the weekends or if working from home I open as many windows as the temperature allows to get a cross breeze through the house. Any bedroom in use should have the window open for at least 10 minutes a day all year round.
I bake my own bread and laundry is dried outside as much of the year as possible. Even in the winter, if its dry hang it outside for an hour - it picks up a beautiful clean scent before it's dried indoors. Laundry is my favourite domestic chore because of how it makes the house smell.
For polishing wood, use beeswax. White vinegar for glass etc. Drains (plugholes) freshened regularly with soda crystals. If you have a stainless steel sink or draining board, polish out any rust marks with a little lemon juice and bicarb.
I like a cheap bunch of flowers with my weekly shop.
On the rare occasion I use a fabric conditioner, I choose wiltons which gives a lovely, gentle scent.
Bicarb of soda in a dish alongside half a lemon keeps the fridge smelling fresh. I'll also sprinkle a little bicarb in sweaty shoes before airing, and you can also use on carpets or rugs before hoovering.
Cotton mattress, duvet and pillow protectors all help prevent bedding getting smelly. Duvets & pillows are aired weekly. In the middle of winter, all blankets, throws, cushions, duvets, get left on the line outside for at least a few hours but preferably overnight, when there's a hard frost. This helps kill any dust mites and keep them fresh. I do this once or twice a winter, depending on ability.
I tend to leave candles and incense to the winter months these days but opt for the most expensive I can afford and choose a gentle scent.
In the kitchen I keep pots of fresh herbs which always smell wonderful - especially mint & basil.
Everyone gets fresh towels at least once a week - more often if they get dirty quickly or don't dry properly between use. They need to be left open to dry, no good folding them up and hanging on the heated towel rail - they end up smelling funky.
Aim to clean wood work (such as skirting boards) at least twice a year. Definitely a chore to enlist your kids for! I loathe hoovering under sofa and chair cushions so I don't do it weekly but often enough to prevent crumbs and stuff building up.
I'm not great at things like dusting but it makes a difference if you keep on top of dust too.