Elvira cake help

Hi! I was watching a Halloween cake battle on TV and I got the idea that I really wanna make a 3D Elvira cake. 3D as in standing like this peppa pig cake: https://www.youtube.com/watch?v=ohOx9JdlC9Q&t=14s

Now, the only problem I’m having is that I don’t know where to start. I have made decorative cakes before but never a 3D sculpture. should I only make the head out of cake or try for the whole body? I’m a little skeptical because she has a very specific look and I don’t wanna mess up around the boob and torso area. Any suggestions on how I should construct this? If you have any tips on where to even start, that would be appreciated. I’m literally just a kid who wants to learn how to make cool stuff :D