A lot of very good ideas and suggestions here. My apologies for not being very good at posting things here.
1. Someone already suggested that keeping a journal should be part of the initial / first badge. I think this should be at the TOP of the list. Herbology is a discipline and like a habit requires repetition. Write it down, write it down, write it down. No one remembers everything forever and when dosing yourself or others 'pretty sure' of the amounts, ingredients, dose, etc. just isn't good enough. Also, the journal would provide additional documentation of the person having completed the badge requirements.
2. Restrict the badge to herbology - it is huge enough without throwing in everything else. It isn't that other branches of alternative medicine and modern/scientific medicine don't have validity because they do and maybe they will become individual badges in the future for those who discover an interest in this field. But for someone starting out, herbology can be relatively simple and, above all, accessible.
3. Which brings me to the next point - accessibility. All plants are not available everywhere - oh wait, this is permies, you all know that
Yes, you can order dried herbs on the internet but is that what we want people to learn? Don't we want them to learn what plants grow where they live that can be useful? I'm not saying it has to be native, I grow all sorts of herbs that didn't originate where I live (zone 6) but there are plenty I grew up with living on the equator that I simply can't grow. So why learn their medicinal properties, make salves and tinctures with them when I have to import them via the internet? So maybe the second part of the badge (after journaling!) would be to determine what medicinal plants are (or could be) available wherever the badge earner lives and their (general) medicinal uses. Maybe this list would be the first entry in their journal? Then, if their circumstances are such they can't actually harvest said plants themselves ordering them over the internet would be an acceptable alternative.
4. Next step would be learning the various methods of preservation - all of which have already been mentioned previously in this thread. Those who have to buy herbs already dried won't have hands on experience with that process, of course, but learning to make salves, tinctures etc. would be part of this step. Oh, and gathering the materials for this step. Need a compress? Better have some pieces of clean cotton or wool material handy. Somebody already mentioned using glycerin in a salve . . . have to admit, I don't have any of that in my pantry. Is there anything else I can use? I might need this compress today, not two weeks down the road when I make the next long trip into town.
Plant identification must be in there somewhere. Practical, by actually looking at the plant, taking a sample of it and pressing it, noting where and how it grows, if at all possible. Theoretical, out of books or online if the student has absolutely no access to the real thing. Isn't the end goal of the badge to be able to say "this person knows how to use herbs for healing"? But if they can't tell the healing plant from it's look-alike poisonous cousin, even in theory, is it a particularly useful skill?
There are so many good reference books on herbs but my favorite to recommend is Be Your Own Herbalist: Essential Herbs for Health, Beauty and Cooking by Michelle Schoffro Cook. It is a smallish paperback so easy to keep handy and she covers basic preparations and ingredients. The herbs she covers are all common ones and easy to find.