Darning is the process of mending wear or holes in knit things. Socks are the usual suspects in darning, but sweaters can also be darned, if the holes are small. The truly creative can make a darn into a thing of beauty. Most people darn for functionality, and I fall into that category. At its simplest, darning is extending the life of a garment by creating a web or mesh of new threads across a hole in the garment. This web is anchored in stronger parts of the item..
Despite the purely functional nature of this craft, I have learned a few tips along the way. First is to darn early and often. If you have a pair of socks that you like --you know, the ones you reach for first in the sock drawer -- check them for spots of excessive wear. Darn them before a hole starts.
Use the best thread you can find. Years ago I was in a store that was closing out silk button hole thread. The last spools were cheap because they were bizarre colors -- mustard, mushroom, royal blue, gross green. Despite the colors, it is beautiful, strong, soft silk that I still use because it works well and I can't feel a darn done with this nice thread. If you can't find silk, save an old wool sock and unravel some of the wool to use for darning. Worst case, use polyester or cotton thread or even fine dental floss.
If you have or can find a darning egg, use one on socks. A darning egg looks like a wooden Easter egg on a stick. Insert it into a sock, maneuver it so the curve of the egg is similar to the curve of the garment and hold the sock and stick with your non-dominant hand. It will provide a stable platform to shape your web of thread and prevent stabbing yourself with the needle in the process. Against the light color of the egg, you can watch your web take shape and make sure you have threads across the hole in several places. This one from Lehman's will give you a visual idea of what you're looking for, but is more of a ball than an egg. It will probably still work. I've also found them in antique malls and second-hand stores.
I try to use a needle that balances the weight of the repair thread and the knit of the sock. Most often I use a tapestry needle -- normally used for needlepoint. Sometimes for a fine knit, I'll use a Glover's needle which is also useful for other repairs, like canvas or heavy denim. Using too fine a needle will make the process less effective and more frustrating. I also tie a knot around a knit at my start point that leaves about 2 inches of thread hanging. I will end the darn at the same spot and use that 'tail' of the starting thread to tie off a secure final knot.
Back to the garment: Find the places at the margin outside the target hole or weak spot (place requiring repair) that are at least as strong as your thread. You anchor the darn there. Starting or anchoring your darn in a weak place on the garment is futile. The darn will not hold and may rip the hole even larger.
Try to get to your holes while they are small, preferably smaller than a nickel but not larger than a quarter. If they are too large, the can't be darned and must be patched or rewoven by someone who knows how to do this. I have a beautiful sweater that I had worn exactly once. I left it where my puppy was able to tug and pull it down. The hole is about 3 inches in diameter. Not a candidate for darning. Some day I will patch it and wear it again with jeans.
Don't forget to add a few darning supplies to your preparedness kit(s) just in case you develop a weak spot in a sock along the way. A timely darn may prevent s painful blister!
So what does darning have to do with being frugal? You have to ask? Oh, darn!