Another one is religiousity or strength of religious belief. Its not a widely applicable rule. African Americans are exceptions to this rule but then they would be exceptions to almost every rule, voting democrat no matter who they are or what they do
Otherwise its one of the best indicators of voting behaviour in the US>
Okay while we are pushing theories here are a couple
The more urban an area, the more liberal. (This actually works in the US but is not applicable in most other places-then again the US definition of liberalism/conservatism that I'm using is not applicable in most places)
Let me know major exceptions in the US.