For myself and the min/maxer of our group (being our first tabletop rpg experience), the easiest way to begin getting into the roleplay is to begin with a flaw or an obvious non-paizo trait and build off that.
For example, the min/maxer guy gave his elf magus OCD. It explains the pursuit of perfection, to a degree, but it also means he's prone to distractions from disorder. The actual player IS OCD, so it may make it easier for him anyway. But giving himself a flaw or an obvious character trait (such as being a outrageous flirt), can really force you into the game. At one point, we had to drag the magus out of a messy library because he felt that he needed to organize it.
Start with that sort of thing and build from there, it can lead to making the campaign that much more hilarious.
