Use the magic markers to label your boxes: "Donate," "Sell," "Return," "Repair," "Keep" and "Unsure." The last container you need is a garbage can. Line the boxes and trash can somewhere where they're all accessible.
Use the donation box for toys going to nieces, nephews or friends' children, clothes going to thrift stores or books going to the senior center. It's sometimes easier to part with things if you know that they're going to be used and enjoyed somewhere else.
Put things in the "Sell" box only if you are prone to sell them. This is for garage sale items, things to go to a consignment shop or an online auction site. This is just another box of clutter if you don't actually sell the items. Mark this box with a date three months ahead and if the items aren't sold by then, they need to go to a good charity instead.
Use the "Return" box for items borrowed from the library, neighbors, friends and family. If you have bought things that need to be returned to the store, toss those in here, too.
Put items in the "Repair" box only if you know they can be repaired. Keeping things that may have some use in them is a trap for clutter. If you think something just needs a little "fixing" to be good as new for someone but that someone is not you, the item needs to be thrown or given away. If you've already replaced an item, get rid of the older one. If you know of no one or no way to repair an item, get rid of it.
Put things in the "Keep" box only if you are sure that the item is really of use or value to you. Otherwise, it goes out. Use the "Unsure" box as a last resort. If something doesn't seem to belong in any of the other boxes, and you don't want to let it go without more thought, put it in here. Mark the box with a date six months away. If you haven't used the item in six months, toss it or give it away.
Use your garbage can for everything you don't need or want. This should be the first place you consider with every single item that you pick up.