Does /tg/ have some tips and pointers when it comes to roleplaying

>>55305840
In order:

Structured ideas and winging it are both valid.

"Subtly" dumb would be, perhaps, someone lacking in common sense. Doesn't close doors behind them, doesn't wipe their feet on doormats, carries too much stuff at once, doesn't check how much ammo they carry, et cetera.

Another way would be the "addleminded professor" angle--instead of being 'merely' book-dumb, the character is extremely articulate and passionate about a certain topic (combat, magic, religion, geography, history...), and totally clueless in other disciplines. They're "dumb", but only in a certain context.

"Intuitive but dim" would be akin to a street-smart character. Perhaps they never finished a formal education. They'd have a good handle on social situations and vernacular, but struggle to define words--or have to search their memory for a word to describe something they're feeling.

(D&D essentially differentiates street/book smarts through WIS/INT--your mileage will vary by the system)

Introducing nuance is like any other attribute to a character--observe their personality and attributes from a new perspective and see what can be adapted.

Be aware that not every group handles 'roleplaying intellect' the same way. Some won't mind a mentally-stunted barbarian solving complex riddles, others will. Take the group into account, too.

>>55305840
Intelligence only means whatever the mechanics of that system make it mean, in D&D, for instance, an intelligent character gets more skill points, is probably better at magic, and is more likely to succeed at certain (mostly knowledge) skills. That is all having high Intelligence means, the rest of the character's personality is whatever you want it to be.