Proper way to enter a Bad Debt

How do I write off a bad debt?

Will a Credit Note work just like a payment?

The only difference is that I need to enter each item and sales price (as invoiced)

Credit Note Type: Items Written Off
Write off item cost to: 5620 Bad Debts

And the allocate the credit note to the old invoice?

I want to make sure the lost income goes to an expense account.

tom