I open several windows first thing in the morning, and leave them slightly open all day unless it's too cold.
If it's warm enough I leave a couple of small upstairs ones slightly open at night.
When it's too cold to leave them open I air the house for 5-10 minute periods during the day.
Always open the kitchen windows when cooking.
Open windows during / after eating smelly food in a room.
Wash cushion covers, curtains, bedding and other soft furnishings regularly. It's things like that, that smells cling to.
Mop hard floors regularly with scented floor cleaner/disinfectant.
I have a wax burner and when I'm at home I usually have it on. I use quite subtle, clean smelling ones. The ones I get from Asda have scents such as 'fresh linen' 'Egyptian cotton' and 'laundry basket'. They smell quite natural like you've just done a load of washing and hung it all up. People often walk into our home and comment on how lovely it smells.
I find plug in and auto air fresheners more artificial and chemical smelling. And the plugs in worry me as I know someone who forgot about it and left one plugged in for weeks. It dried up, overheated and set on fire causing substantial damage to their home and nearly killed them all. They are also useless at getting rid of smells they just mask it for a bit. Cleaning and fresh air is better.