from books and what I remember of a long-ago 8th grade home ec. class. I remembered to lock my stitches and how to sew a hem. That was about it.
I've made a couple of t-shirts, and even adjusted the pattern. That wasn't hard because it had a line saying "add length here" which is what I needed! The one I chose also has three choices for collars and sleeve lengths - which makes it very flexible. The shirts I've made are comfortable and look good. None have sleeves yet, because when I tried to add them I found out they won't fit me without adjusting the pattern. While I do have a book that tells me how to do it, I haven't been that brave yet!
I've also modified pillow cases, made a couple from an extra sheet, and done some basic repairs. If it's fixable and not something I'll be heartbroken to loose, I'll try fixing it and count it no-loss if it doesn't work. So far, so good!
Have you tried to teach yourself something new?