Here’s a quick one that will make your life easier in some cases. Certain garments, like a Tuxedo Vest with pointed hems for example, really need careful placement of the buttons to make sure that those points stay even. When making my son’s prom vest, I sewed the buttons on the front from the top down. I did a great job spacing them, but when I got to the bottom I saw that they were placed so the points were just slightly askew. He probably wouldn’t notice, but it made my eye twitch, and I’m sure it would cause my sewing friends to give me side eye. So here’s a quick solution: sew the buttons from the bottom up!
First, of course, I sew the button holes. Then I lay the piece on a flat surface like an ironing board and using a ruler, “level” the points:
Position your bottom button based on this, and sew it on the garment. Then you can move up the garment and sew your buttons on. Ta daa! Points are aligned!
Now obviously, this works best on a garment, like a vest, that has a v-neck. It’s not meant to replace precise cutting and sewing, but it will make it less likely that you come to the end of the buttons and discover that you’re off by a minute but irritatingly visible amount.