How do I wean myself off an antidepressant properly?

Stop antidepressant? Changes in dosages of medication that you have been prescribed consistently over time should not be attempted without a doctors supervision. So, just like you would see the doc if you though you needed to increase your dose, you should see the doc and discuss dose reductions with him as well :)
Depression. Discuss with your medical doctor to determine if weaning or tapering off a medication is appropriate. If weaning is ok, then the medical doctor will provide a tapering schedule to avoid withdrawal symptoms.