The best way to clean a cluttered house is to get four boxes and label them "Put Away," "Sell," "Donate," and "Storage." As you work your way through each room, pick up items and put them in the appropriate boxes making sure to put any trash straight into the wastebasket, and recyclable materials into the recycling bin. Then you can begin the actual cleaning of your home.
The key to this method is following through on the four boxes; putting items away, selling/donating them, or putting them in designated storage. As you go through each box, ask yourself if the items are enhancing your life. If they are things that simply sit around in a cupboard and collect dust, do you really need them? Does the thought of them finding a good home with someone who will use them make you happy? If so, then it's likely that selling or donating the items would be a good idea.
Maintaining a clutter-free home makes keeping it clean much easier. Have a designated drop-off area for mail, backpacks, and keys. Put all junk mail and other recyclable materials straight into the recycling bin. The more things you have taking up space on your surfaces, the more dust will collect, and the harder it will be to keep the area clean.