This wouldn't be called a guide per se, it is just a tip you might figure out on your own. But for those who want to know it earlier or just missed it, I will say it:

In order to get the max amount of money from a fight, you have to focus on making your combo higher. I cannot give exact numbers but for example having 15 perfect, 15 good, 30 combo is better than say, 25 perfect, 20 good, 10 combo.

Also the max amount you can get for the technical part is twice the amount of the fixed reward.