How did learn this skill? I first needed a sewing machine. I read a fair number of reviews, couldn't understand why so many individual models are marketed by sewing machine manufacturers, and ended up getting a
Brother CS-6000i new for $150. That's relatively cheap in the sewing-machine world, and it seemed to be described as a good value for the money and had lots of really good Amazon reviews. So far it's done everything I've needed it to do (and even quite a bit more...haven't found a use for most of the wacky decorative stitches yet!) Surely even better values could be found on Craigslist, particularly since basic sewing-machine technology hasn't changed much over the years. Though the one thing I would miss in an older non-"computerized" machine is the ability to automatically stitch buttonholes.
Another "new technology" thing I'm happy to have sprung for is a
rotary cutter (and
self-healing mat) to cut out fabric pieces. It must have been way more annoying (and less-accurate) in the old days to cut things out with scissors.
Then I went to the library and checked out a couple of general sewing books to get an idea of the basics. I don't remember the titles, but I think most libraries would have similar books (though it's funny/annoying that at least in my library, the sections for 'quilting', 'embroidery', and 'knitting' are each like 5 times the size of the straight-up 'sewing' section).
A related annoying thing (as a guy) was discovering how female-focused even sewing books are. I saw one pattern book where there were 10 sections, and the 10th was "Men's and Children's Clothing". Men don't even get 1/10th of the book to themselves! Luckily, David Coffin was there to rescue me with his excellent
Shirtmaking: Developing Skills For Fine Sewing. The book goes in-depth in both basic sewing techniques (at least those required for the task at hand), and in detailing specifically how to design, fit, and construct men's dress shirts. Most importantly, he very much has the same philosophy as I do in wanting professional-looking results, so he has researched the way the real tailors make shirts and how they're different than some of the methods instructed in home-sewing patterns you might buy.
I also then got his
Making Trousers, and it's helpful, but is mostly an exploration of different design options and contains very little about sewing techniques.
Google searches taking me to various sewing blogs or YouTube videos have been helpful from time to time as well, when I encounter a specific issue or have a new question pop up.
So, is sewing your own clothes a Mustachian thing to do? From a financial perspective, no. Home sewers, buying at retail, pay extremely inflated prices for various things. I can get an entire shirt at a thrift shop for the price of a set of buttons on one of my own shirts. A Craigslisted sewing machine might pay for itself over time though, because once you have it and know how to use it, you can find lots of other things to repair/tailor/create besides from-scratch clothing.
But I maintain that it's totally Mustachian from a DIY, teach-yourself-new-skills perspective. Given how female-biased the activity is, I was surprised to discover how it's actually a very "manly" thing to do. It involves a whole lot of geometry, math, thinking in 3D-space, operating complex electric machinery, following detailed instructions, etc., all things that we're supposed to believe women are utterly hopeless at! It's basically the same thing as the manly sport of woodworking, except you're designing and building things out of cloth instead of wood. Unfortunately, unlike MMM's welding, I don't think it's quite a skill that can lead to riches, since you'd be competing with an enormous worldwide clothing industry that has FAR lower costs.
But if you're a tall, thin guy who is interested in attracting members of the opposite sex, then I would say that, if not quite Mustachian, it can be at least help you achieve your goals more-economically than paying someone else to custom-make your shirts!