I learned in the military. Never anyone around to sew patches on, had to do it myself! I even bought a used sewing machine and learned to use it. Handy when I need a stuff sack or a specialized pouch.
For basic repair and improvising, the basic stitch should be adequate. I carry an Exped sewing kit, like a mini sewing awl. Comes with directions. It is a copy of the old Chouinard expedition sewing kit, handy items!