again... it varies. im just gonna try and explain the method thats most beginner friendly lol.
you can see the base structure for the body in these images (click to enlarge).
first of all you should make the head (its shown in the videos so i wont explain any further). after that you can base the body proportions on that. it helps making a true to size sketch first (i made the head to big in the second img lol). after that you can make the hands and feet with clay and stick a piece of wire in them. then you make the body out of cardboard, tin foil and hot glue. the first img explains it pretty well.
legs and arms are made by wrapping paper with hot glue around the wire. after that you should make the clothes. get him dressed before you attach the hands, feet and head. and thats it basically. im kind of assuming you already have some experience with crafting stuff... cause this is a somewhat advanced project. if youre a complete newbie in sculpting, sewing etc maybe try making a more chibi like character like a clown first its way easier and you dont have to use the cardboard body only wire and stuffing is enough.
in general characters who show little skin are best and easiest to make. at least have the joints covered with something to hide the wire. also these dolls are somewhat fragile so i advice keeping them on a shelf and not posing them too often since wire breaks over time. you can handle them tho like.. its fine just dont drop them.