The first thing to do to be a good trooper is to use your troopers. Every one of them. Not just those you feel are powerful, but every one. And do so every day.
Second, set a strong character as your champion. This doesn't mean it has to be the most OP toon in the game, but it should at least be a character with skill shards applied and talismans leveled up.
Third, be responsive. If someone asks you to share a certain character with specific talismans, it's a great thing to do.
Basically, play the game daily and use your troopers. That's all that's really required.