Learn about (your) local plants, wild plants, for herbal/medicinal use.
It's possible in a post TSHTF world, doctors and pharmacies might not be readily available, if you have a working knowledge of your local wild plant life that can be used for medicinal uses, it could be a life saver. You can also use this knowledge for bartering purposes. Plus it's just plain fun to go out and harvest good things from nature.
Try to learn about at least one a week, go out in your local area, identify the plant life, then look up what those plants are good for. Here's one, pine trees, the needles are full of vitamin C, you need never get scurvy if you have these plants around you, Just grab a hand full of green needles, plop them in hot water, steep to make a tea, strain and drink up.
The sap or resin of the pine tree has antibacterial properties.
There, you know one now, so now it's your turn.