Divide and conquer your kids toys.

Big toy boxes make it too easy for toys to get jumbled together.  A better idea is a bin for legos, another for action figures, another for barbies etc.  Another idea is a set number of tubs with lids and only one tub is allowed out at a time.  When new toys come in old toys must go out to make room for the new toys inside the tubs.

You can also rotate their toys.  Teachers say kids concentrate better on their play when they have just a food good toy choices.  Keep extra items in your garage or basement in tubs marked "toys on vacation" and swap them out every few weeks.

Your house will be instantly neater.