Also, have a 'one in one out' policy for toys, my ds takes them to the charity shop for 'the little boys who don't have any toys'.
Totally second the storage thing. All ds toys are in different bags/boxes. Cars in a small old suitcase/motorbikes in a lunch box bag/bigger vehicles in a basket etc. This makes putting away / finding things easier and is much nicer to look at than a mad jumble!
Love the idea of litter trays for paints and stuff. Also, for older kids have a 'tidy up time' perhaps just before tea. Then whip round with a basket afterwards and anything not put away goes in there; charge minimal 'fine' to get things out!!! Mondey can go in a jar towards family days out etc. Will make loads of money from dh no doubt!
Use a timer. Often, when things are a total bombsite, you can't face starting as you think it's going to take ages, and then if you do start, you get sidetracked reading an old paper or whatever. Set a timer for 15 mins and stop when it goes off; be creative, stuff that goes in another room, don't take it then just put it by the door to take after the timer goes off. It keeps you focused - it really works and it is totally amazing what you can get done in that time.
Oh, and instead of staring into space while the kettle boils or you're waiting for the microwave, start unstacking the dishwasher or peel a few spuds for tea etc.
And finally, when yr watching tv in the evening, tidy when the ads are on. No tv here but dvds etc, but pause every 15 or 20 mins for a few mins and tackle some tidying if it needs doing, rather than feel like a martyr and not sit down till it's all done, or sit fuming in a pig hole.
All strategies that help me, hope they help you.