Obtaining a highest fame rating requires that you simply use a character that is of that nature, or by completing skirmishes that reward that type of fame. There is also an option to take jobs from your lord if you're an officer which reward additional fame of different variations. Each of these fames can go as high as fame 9, so you'll have to take part in many battles before unlocking each respective trophy.
It is advised you only do one of these fame choices per playthrough, as there are trophies also tied for seeing endings which are determined by your highest fame.
Affluent characters receive perks that help them build their bases up during battle, along with promoting wealth. If none of the characters suit your interests, I suggest creating an officer with the affluent trait in a style you enjoy that way you receive fame points for this particular trait after each battle while using a moveset you enjoy.