Restoring minifig parts to original configuration for sale
You may use the minifigs section of Brickset to help you. They have reference of over 9000 minifigs released by TLC over time. By browsing per topic, you may complete some of your minifigs and using the site is completely free.

There are also several books like this Complete Lego Minifigure Catalogue (1975-2015), even if books may offer a higher challenge to search. Moreover, books are not free.