Put away things where they belong, don't dump them on a chair/floor to deal with later. Especially with children, make sure they have some kind of storage for their shoes/coat/bags when they walk in.
Don't have a messy kitchen: only keep the things you are using outside (kettle), everything else in cupboard. I empty the dish washer first thing in the morning, so there's somewhere to put the breakfast dishes before I leave.
I could not agree more with fitted wardrobes, they make a room look tidy but make sure it's not a mess inside.
Plan practical storage for everything. You know your life, if you receive constant letters and emails from schools for example, have somewhere to put them all until you deal with them.
I have a big calendar, with different columns, where we write everything. An online calendar wouldn't work for my kids, so we use the old fashion one. I have my own diary with all the details.
I never have to tidy when I have visitors: it is what it is, if they don't like it, they don't have to say, but in general the house is more than presentable. Why would I make more effort for someone popping in for an hour, but not for us who live here?
For me, having storage and be realistic about the way we live is the most important thing.