>>96161520
A couple of thoughts
>don't make him a couple of hundred years old
Unless that edition or your GM enforces him to be this old. If you have trouble with portraying such an elf, then play a relatively young elf. Elfen culture and elfen psychology should still affect them, even at a young age.
>time horizon
Always consider the long term effects of your and your party's action. Regardless of your age. I don't care about the setting and lore, a being with such a natural long lifespan should naturally consider the long term effects of their actions. Think about big pictures.
>keep your distance
I won't tell you to play an arrogant, aloof asshole. But the distance to the other races lifespan should make you naturally more aware of the differences. Maybe try to not get too attached to the others AT FIRST. If your elf warms up to the others and swears friendship, it should matter. It could make for a great arc. Maybe don't take human laws, institutions and customs too seriously.
>don't overthink it
Just play a character that you find fun and are comfortable with. You aren't writing a novel, nor are you expected to be a professional actor.