If you have the bad luck to be audited, how will you prove that you gave items to Goodwill or Candlelighters? A receipt from them says you made a donation. But the IRS knows that you get to fill in what was given and how much it is worth.
I tell my clients to take pictures of the donated items using their smartphones or digital cameras. That saying "a picture is worth a thousand words" is really true here. If I can show the auditor pictures of what was donated (preferably with the Goodwill truck in the background), it is much harder for them to disallow the deduction.
Like any good CPA, I need to add a disclaimer: Unfortunately, it is impossible to offer comprehensive tax info over the Internet, no matter how well researched or written. And remember, I love my readers but having me bookmarked on your computer doesn’t make you a client: before relying on any information given on this site, contact a tax professional to discuss your particular situation.