Photocopy Your Receipt
If the item you purchase has a warranty/return policy of a year* or more, photocopy the receipt. This advice was given to me when I was buying a watch. It is because of the paper and ink many stores use with their receipts. I was cleaning out some files and noticed that I couldn't read many of the receipts and this was from a different store.
* it could even be a shorter period of time.
* it could even be a shorter period of time.