Use a Filing System:
A filing cabinet or expandable file folder is the easiest way to keep information organized. The amount of filing space you need will depend on the amount of warranties you have acquired.
Label Your Files:
If you only have a few warranties, a single file labeled 'Warranties' will work. If you have many, you can categorize the files by type. For example, 'Appliance Warranties' or 'Computer Warranties'.
Attach the original receipt (or a copy if you need the original for tax purposes) to the warranty, preferably stapled.
Keep the warranty (attached with receipt) in the file folder until you need it. This will save you a lot of grief the next time you have to locate your warranty.