I am a bit of a domestic goddess and do live in a very tidy house. My tips are:
Obviously clear out any clutter you do not use. Get rid of clothes and toys that are no longer wearable/usable and be ruthless. A jigsaw which has a piece missing won't be used again. Try (if you can afford and have room) to get a cupboard that will house all the kids toys.
Have a place for everything.
Do a load of washing every single day, then it doesn't mount up. Make sure you put it all away as soon as it is dry and doesn't need ironing.
Have a junk drawer in the kitchen. Throw all the shite in it that is on the worktop and then every few days, when you have a spare 10 mins, go through it and bin anything that isn't important. Make sure you have a pinboard in the kitchen for important paperwork. Try and keep your work surfaces free of clutter, it is amazing how tidy your kitchen can look when it isn't full of crap you don't use.
Every time you go upstairs, take anything with you that needs to be up there and put it away.
When you have a shower/bath, when you have finished, put all your bottles away so they are not cluttering up the bathroom.