When I studied medicinal herbs, Oh so long ago, my teacher suggested that I start by studying herbs that would help myself day to day (it helps motivate you to undestand it deeply). What types of illnesses and/or injuries would I be expected to have, or have family/friends to have? For myself, I used to have nasty issues with allergies, and arround that time I served apprentiships with a master blacksmith and a tool and die machinist -- suggesting a focus on herbs that deal with allergies, inflimation, burns and cuts. For someone on permies, I am guessing that we are talking about typical gardening, forestry, and animal husbandry issues. I am guessing that would include the allergies, inflimation, burns and cuts mentioned befure plus different infections (both fungal and bacterial)...
Early on in my studies, my teacher held up a couple of "herb books" (each with 100's of herbs in them). She explained that traditionally even experienced healers never knew more than a dozen or two plants, and maybe a hundred or so preparations from those. So, start with a couple of plants, and see how deep you can go.
On last thing - start with things that are not dangeriously toxic (like digitalis and mistletoe - whose dosage calculations are life and death critical). Also start with something you can grow in your garden (or a container), so that you become familiar with every stage of the plant (including harvesting and preparation).
While this is not a list of "try these", I hope my comments help.