Donating old clothes to charity is a great idea for many reasons. It's a great way to de-clutter your closets and drawers. The environment also benefits since clothing thrown away rather than donated ends up in the landfill. Donating old clothes can be especially helpful to society as people who need affordable clothing often have access to donated clothes.
Make sure that the clothing you donate is wearable. Yes, there are people who really need affordable used clothes, but nobody should have to wear stained or ridiculously outdated items. Look for a place that recycles fabrics and/or use stained or dated old clothing for rags for household cleaning and dusting. Stained, but clean towels and blankets are often appreciated as donations by animal shelters.
The best time for donating old clothes is just before a new season starts. You can clear your closets and drawers of clothing that you won't be wearing any longer and make room to buy new clothes. And when you donate your old clothes in season, the secondhand shops and other charities will be able to distribute or sell the clothes faster rather than having to store them for another season. Smaller organizations especially may not have a lot of storage space.
If you have some really special pieces of clothing to donate such as a glamorous evening outfit or a collection of career, maternity or baby clothes you can often find special programs in your area in need of these items. For example, many communities have an organization that offers good used prom dresses and suits to high school students. Some cities have employment programs to help people find work so you may want to help by donating old clothes that are still appropriate for job interviews and office environments. Baby clothes and maternity clothes can be donated to parenting groups or programs for young mothers.
Some secondhand stores accept clothing donations on consignment. This means that when someone purchases your items, you can earn cash or store credit. This can work out especially well if you buy secondhand clothing from the shop anyway. This way you can almost trade your old clothing for new clothing while keeping your costs at a minimum.