Use nonpoisonous herbs whenever possible. See substitutions list LINK THIS SITE.
Wash hands and utensils well after preparing and using these herbs.
Label your bottles and containers with the name of the herb, and with something to denote that it's poison.
Keep out of reach of children, pets and all other unknowledgeable persons.
Try not to inhale these herbs. Don't breathe the powders, or use in incense unless outdoors.
Keep away from any cuts or abrasions on your skin...that's a quick entry point for the toxins.
KNOW what you are doing if you do choose to use the baneful plants.As these herbs are highly dangerous on the physical level, so too are they dangerous on other nonphysical levels. Take care with these.
Respect the Baneful Herbs and use their magick wisely.
And of course, don't eat or drink them.