If you haven't finished Burgerninja already, do that. Just once.
Finish Wasteland once as a White-eye, once as a Redeye, and once as a Legacy. This will take 3 seasons.
Finish Reaper AND Monochrome once as a White-Eye, once as a Redeye, once as a Legacy, and a fourth time to get Eclipsed. This will take four seasons, and you can do Monochrome and Wasteland at the same time.
Also, start paying attention to achieving Top 3 or Top 1 status. Each time you get Top 3 status, you can do the quests "2 B A Master" and "Cashing In" once per season in order to get a Pirate Hat and the 9 Golden items. That means you'll have to have to do it once each season for ten seasons ... unless you get Proof Reader in Season 4, but don't get ahead of yourself.
Achieving Top 1 status will also be helpful down the road, and if you luck out and get it early, well, then you won't have to work extra hard for it later. NOTE that it works like this: You make your Top 1 run on Monday morning, and then you get ranked #1 on the Highscores page on Tuesday. On that day (Tuesday), you have to loop in order to get the theme "Out On Top", which is the real prize.
Don't start worrying about R00t until you're at least Season 4. Same with Pizzawitch.
What else is there ... Robo Fighto. Uless you absolutely hate it, you should start after you compete Burgerninja once. The Corrugated G-Rank parts are optional but recommended. The Tinfoil F-Rank parts (except Tinfoil Bikini) are a must when trying to get the Foam E-Rank parts. And you really, really, really need all the Foam parts if you want a snowflake's chance at the Tiny Bee Pistols 2.0.
As for Mahjong: If you have gotten to level 3 already, either you're spending boatloads of money, or you're really good at it. Possibly both.