Monster Hunter: Wilds had several betas, including two weekends of open beta, which actually featured the start of the game and the full character creator. However, when you start the game, you have to repeat that short section, a chase scene through the desert.
The one thing that you can keep, however, is your character design (only the external design). After two cutscenes, you will go to the Character Creator screen. Then, Choose hunter or Palico and then, at the bottom, you' find the option to Transfer Data from Beta.
The one thing Capcom asks is to do it when the full game is fully downloaded and installed, not before.
It is that simple... however, you have to do it at that moment. If you create a new character, but later you want the beta design, you will have to use a Character Edit Voucher or Palico Edit Voucher. You start the game with one voucher for each (your hunter and your kitty companion). However, if you spend...
In your camp, you can choose to change your appearance. That is for hair, make up, and a few other things, but if you want to change your character completely (skin, head, nose eyes, ears, voice and, while the game doesn't explicitly say it, gender) you have to do it in the Main Menu. In the Data Select screen, before starting your game, you can press Square/X to open the character editor... spending a Voucher.
That includes the option of transferring the design from the beta, if you have the data, as well as creating a new one. It offers many more choices than what you can normally do in the camp, including genre. While the game no longer separates "Male" and "Female" hunters, we found that the option to change hairstyles in the camp was limited to "Male" or "Female" hairstyles, even if they weren't labelled as such.
And how do you get character edit vouchers? There's no way to get those during gameplay, only by paying: it is paid DLC, just as it happened with Monster Hunter: World. At the time of writing, we still don't know how much they'll cost, but we can assume it will be the same as in World, 3 euros/dollars/pounds...