Putting on a character, a bit like a suit, is a technique from acting (method acting) that can be useful for gaming. Instead of thinking what you, the player, would do in any given game situation, put yourself in the mindset of your character and think what they would do in that situation. Ideally you do this regardless of your considerations as the player, in terms of the game mechanics.

This is not by any means a revolutionary approach, and many roleplayers already do this to some extent. But if you haven't tried it, give it some thought. To do this successfully, you need a well-developed sense of who your character is, what their background is, what motivates them, and what their desires and goals in life are, and so on. Even if you don't go the whole hog into method acting your character, at least thinking about the background like this can certainly help in roleplaying.

Transcript

Chewbacca: I'm going to go insane here.
Salacious Crumb: Oh, yeah. Woe is you, who's just been forced to entertain Its Majesty for all of one hour.
Chewbacca: Splendid. The halfwit monkey-lizard creep using sarcasm. Hallucinating already.
Salacious Crumb: Listen pal, you wanna survive here, you gotta keep it together. Take my advice. When you get dressed in the morning, the real self, the you inside the suit, you just put him to sleep. At the end of your shift, you wake up again. Simple.
Chewbacca: What? You're in a monkey-lizard suit?
Salacious Crumb: Don't start thinking you're special, pal. Everyone's in a suit.
Chewbacca: What even are you under there?
Salacious Crumb: Hmmm. Okay, big fella: I'll tell you if you tell me.
Chewbacca: But... I'm not in a suit. I am actually a Wookiee.
Salacious Crumb: I get it, method acting. You're a "Wookiee".
Salacious Crumb: If such a thing even exists.
{beat}
Chewbacca: I'm going to go insane here.