All you really need to know is where to put the seams, it’s usually very logical to figure out–like a character’s arm, you’d put a seam around the shoulder and the wrist, and then a line along the bottom of the arm, and that would unwrap like a cylinder. For the hands you’d run loops from the wrist along the fingers to the other side of the wrist and you’d end up with a top and bottom to the hand. Stuff like that, not difficult once you get used to it.