I sewed all my clothes when I was younger and patterns were simpler. You could buy a size 10 and get a size 10. Patterns now have several size markings on the patterns (from 6-12) and I have a hard time following them or cutting on the correct lines. I would rather make a dress or skirt from scratch than have to alter ready-mades. Ready-mades are made for tall thin young women rather than 5'2", 157 pound, seniors. If you were able to buy a vintage pattern, you are in luck. Go for it and learn.