Although there are exceptions, for stamps to have value (above face value) they should be mint prior to 1925 or used prior to 1900. We buy later mint stamps generally in large quantities. If you’re selling classic US stamps, it would be to your benefit to get them certified. If you need help finding a reliable certification service, Dave would be glad to advise you. Depending on your location, you may want to scan some of your stamps and the certificates as well if you have them. Dave would be glad to review them. If you wish to wait until Dave will be in your area, please let him know what city you’re in and you can discuss it further.
If you inherited a collection and know nothing about stamps, feel free to scan some photos of your stamps and Dave would be glad to get in touch with you and email you some advice.