You can limit the skills characters can select based on the nature of the campaign. For example, in a campaign where characters play as crew members of a starship, you can designate specific roles on the ship that use specific skills, like captain (
Diplomacy), doctor (
Medicine), engineer (
Crafting), and pilot (
Piloting). You can delay the benefits of the variant rule until after campaign roles are formally assigned, especially when using the variant rules in tandem with the Level 0 Character rules.