There is really no right way to do it. You don’t even have to do it. It all depends on whether you want to plan beforehand and whether you’re struggling to fully understand your character.
A lot of the following fields don’t have to be filled in, just think about it. For example, the number of siblings – if you know it’s two, then that’s fine, no need to write it for the sake of it. Some of these things may not even be relevant to you, it really depends on the story, so be selective.