When I started, I RPed older folks; usually tried to be the voice of reason, caution, calm, and forgiveness. Typically backed-up with broad skillset already mastered.

But as years went by I decided to get reckless and RP younger characters for an added spike in difficulty as those characters had to learn things I as a person already knew, typically the hard, painful, and often in embarassingly-amusing ways.

This has kept my median roleplay-age somewhere around mid to low twenty-somethings unless RPing races that live ridiculously long (or short) lives.
-With exception to the wheelchair-bound 75 year old badass-grandpa in power-armor.