Its actually quite simple. Take any culture and for the sake of an example I'm going to use Texas (it seems appropriate). If you think about Texas a few things might quickly come to mind.
- Big; the state is huge and anyone who lives here gets used to that fact. Which means they don't think about driving 10-25 miles to get the simplest things or drive 50 miles to go game with someone. Its a part of the social fabric of the state. So, we might have a cultural influence here revolved around travel, where the influence handles a factor of travel.
- Large amounts of land; texans are known for everything big and owning land is one of them and not in tiny lots either. This could be another influence if desired; one with unlanded nobility as a possible or anything else that seemed appropriate.
- Patriotic; You can throw a rock and not hit a Texan that hasn't or is currently serving in the military, government or some community organization. National Charge, National Pride and other like nation-based influences are very appropriate here.
- Border Life; Texas sits on the borders and this influence is a good one to incorporate.
- Multiple large cities; Texas has numerous large cities so any of the serveral urban based influences are appropriate
- Commerce; Texas has a lot of commerce and several of the economic and business influences could be incorporated
- Resource Rich; Texas is rich in resources and you can make influences that revolve around the acquisition, movement and sale of such things
Can you think of more? This took only a few minutes and is a slice of the conversation I had to show them how to craft their own influences for the cultures of their favorite game world using a real world example.