Step 9 = Let fresh air in!
How does your house smell when you first go in? Stuffy? If so, then you could be damaging your health by breathing in stale air and allergens. Stale air can make you feel tired, headachey and can even lead to feelings of depression and anxiety.
Ideally your home should have air flowing through it 24 hours a day, whatever the weather - yes, the above photo does show snow on the window ledge of the open window! Some people leave a couple of their upstairs windows locked in a slightly open position (bathroom and bedroom windows, ideally on opposite sides of the house to encourage a through-draft), others have window-based fans installed, others have window frames with in-built vents. Leaving the internal doors open in a house allows air to flow around the house, into rooms without air coming directly in from outside.
If you can't face the thought of a constant draft, then at least get into the habit of opening the upstairs windows (if they are safely away from climbing children) as soon as you get up in the morning. Then of course go around and close them before you leave the house. Do the same when you arrive back home. (If you only have downstairs windows, you will need to invest in window fans and / or window vents, to keep the air circulating as it isn't advisable to leave ground-floor windows open unattended whilst you are elsewhere in the home).
Invest in a good bathroom extractor fan (which continues to run for at least 30 minutes after the light is turned off). Plus, always have the bathroom window wide open, if safe to do so, (and the door shut) when you are showering (and when you run a bath), as the clouds of steam generated carry a huge amount of moisture.
For those with serious window-condensation problems, EnviroVent is the company to call. They fit heavy-duty fans in bathrooms, kitchens and hallways to ensure airflow, thus solving damp and mould issues associated with water-saturated air.
A damp house isn't a healthy home. So, one way or another, let the fresh air in!