The first issue is that Canada does not have a 'defined' method for deeming someone resident or non-resident. It depends on a series of variable factors and each case is looked at individually.
CCRA will look at all of your ties to Canada. For instance, if you own a home and it is empty or rented to a family memeber than you will most certainly be deemed a resident. If the home/property (or properties) are rented arms-length (ie. not family) then they are considered investments. You pay tax on any profit and that is it.
If you keep your health card then that would also deem you a resident. So the trick is to rid yourself as of as much as you need to in terms of ties to Canada. If you plan to rent property then it would be OK to keep a bank account (for example) to have the rental cheques deposited to. Otherwise close the bank account.
After we left we continues to get the family allowance cheques (all $8). We sent them bacj to CCRA with an expanation that we had left the counrty and they nicely sent us a letter saying we were considered non-resident and would not be recieving future cheques - VOILA - in writing, from the CCRA that we are non-residents