I had no intentions of joining the visible mending club... until I bought a superfine merino wool sweater at Goodwill, and took it out of the delicate cycle with what seemed like a million holes.
Oddly, the holes are just on the front of the sweater, and the sleeves. I'm not sure if you're supposed to use an embroidery hoop when darning like this, but it seemed the best choice for such a fine knit, and helped me see what I was doing. This isn't quite like darning a sock where you put something rounded under the hole. I used a mixture of techniques including an embroidery star stich, weaving, and mix of Scottish and Finnish darning. It took me a while poking on the internet to figure out how to darn, as the people currently teaching it aren't in my country and are charging for their expertise as teachers. I get it, I've paid for my share of classes when I want to learn something new, but I'm also the person who will try to figure it out for herself.