Here's an idea that makes it easy to get rid of things: place a shopping/grocery bag in each closet in which you can deposit items no longer wanted or needed.
Don't forget to put a bag in the laundry room, too. As you're removing clothes from the dryer, it's so simple to get rid of outgrown children's clothes if you have a bag right at your fingertips.
If unwanted items are to be trashed, take them directly to the trash can. But if they are to be donated, drop them in your bag. When charities call, you're ready with your bag of donations! Empty out each bag and start fresh.
If you find your bags are overflowing and want to get rid of your unwanted articles quickly, toss them in your car so you'll remember to drop them by your favorite charity.
If your hand-me-downs are going to a particular person, label the bags accordingly and put them in your car so you'll have them on hand the next time you see that person. Better yet, drop them off personally and get them out of your car!
More on decluttering and donating: