Choose a small map and 10000 gold, 5000 if you know how to play but 10000 gives you more time to make sure you win.
Move around the map, buying property similar to Monopoly, and collect flags, when you have all three flags return to base and level up and get some more money, rinse and repeat.
EDIT - DISREGARD FALSE INFORMATION
Getting good roles can be annoying, so add other controllers if you have them, otherwise you're stuck with the AI.
Mini games are a bloody annoyance, pay attention to if you're top screen or bottom screen, as that can waste time, also if you draw the defender wins
Steal - run around grabbing coins, go for larger piles if you can otherwise go for grouped piles.
Destroy - break the boulders, the brown ones only require 4 hits, the grey ones require 6, ignore the fish they require 8 and waste time.
Race - break through the screens, there are three choices, one explodes, one doesn't break and the last breaks easily, there are seven sets of screens and whoever is further wins.
Reveal - Kind of annoying, run away from the two officers and jump and press Y, this ground pounds and instantly kills the sky ninjas, which.. hide... underground.
Annihilate - Kill as many people as possible, play until you get a full musou bar then unleash it.
Chase - Run after the fire ninjas and kill them, rather than run round the edge, move into the middle and cut them off, they tend to group up, so you can get four at a time.