Shred canceled checks and debit/credit card receipts as soon as you reconcile them with your bank or credit card statements.
For tax documents, the conventional wisdom has been to keep them for at least seven years before you destroy them, but IRS spokesperson Dan Boone said that's changed.
"IRS recommends keeping tax-related records for at least three years past the due date of the return involved," said Boone. "For investments, we recommend keeping the records for as long as you own the investment and for at least three years after you sell it.
"Generally if you are going to be audited, it will happen no more than three years after you file the (tax) return."
If you're shredding at home, make sure you use a CROSS-CUT shredder that slices the paper into 1/4-inch or smaller confetti. If you use a shredder that just cuts the documents into long strips, thieves can pieces those back together, either by hand or by computer with specially designed software.
Wholesale clubs like Costco and Sam's Club sell cross-cut shredders for as little as $45. They should be able to cut CD's and floppy disks, too.
Consumer Reports recommends using hard-drive shredding software or removing the hard drive before you sell or throw out a computer.