there have been just a few times i darned socks, here is my not so expert advice and lessons learned
1-- get 100 pairs of socks to put away so you dont ever have to darn
2-make sure to get good darning needles and thread-yarn
3-watch a couple videos on how to do the stitches
4-buy some more socks to put away
5-you can use a light bulb, darning egg, end of coffee cup (emptied preferable), the bottom of a plastic soda bottle or similar, whatever you are most comfortable with using and have available.
6-say a prayer and stitch away
7-buy some more socks
i guess i was a lousy darner, and that was back when i had good eyes when i loved sewing , quilting and weaving stuff. the spots i tried to fix rubbed against my foot in time and never felt right.
i agree it is a smart thing to learn to do.
but it doesnt hurt to buy more socks just in case.