Some quick notes about the Mahjong minigame completion requirement, which is one of the hardest to achieve:
You start with 25,000 sticks and your goal is to get to 50,000 sticks by the end of the game. The 50,000 does not include 1st/2nd place bonuses applied after the end of the game.
You will probably find it helps a lot to switch from the default "quarter game" setting to "half game". This doubles the length of the game and gives you more chances to build up a score.
You're probably better off trying for 50,000 sticks in the ranked competition at the Mahjong parlor in Kamurocho. Why? Because you're probably going to be trying many times, and there is no cost to participate. If things aren't going well for you, just quit the minigame and try again -- no harm done.