For years I have made donations to Goodwill and received a generic receipt. And now I know what to do with it.

Goodwill has a Valuation Guide to help you put an amount to what you donated and can claim as a deduction. (always speak to your accountant and/or tax advisor for clarification)

I personally created an Excel Spreadsheet with the different categories, values and a simple formula to add up my total deduction. This is the final sheet that I will keep and provide my accountant when I do my taxes

Here is a link of the excel xls file for you to use

Here is an excellent video explaining what can be deducted and how