Self Insurance is when you charge a little big extra on the item price or shipping price and then you save that money to cover the few times you will have to replace a lost/damaged shipment.
There are 3rd party insurers like InsurePost (owned by ShipInsurance)
http://www.insurepost.com/Default.aspPage 110 of this thread has good information on how to use InsurePost:.
www.etsy.com/teams/7654/etsy-international/discuss/6779956/page/110
Any more questions about InsurePost?
go to this blog that has compiled a list of topics from this thread
sproutluv.com/noted/etsy-canada-post-shipping-superheroes-luv-and-t...
Then scroll down to INSURANCE, then InsurePost and there are links to some exact pages in the Canada Post Shipping Thread where Insure Post is discussed.
I would suggest you self insure low value parcels, and use a 3rd party insurer only when shipping higher value shipments (you decide, many sellers insure orders that are valued $50, or $75, or $100) or on transactions you are concerned about, countries that have a poor reputation on postal service (example Italy).