First is to learn how to work shift-puzzles. These can get you around 3000 NP per character, but only if you are good at it (my record is 3500, but they changed the amount of money it was worth, so now I'm only getting around 3000). The main keys in beating these puzzles are to: a) Play ALL of the levels, b) Start at the top left corner and go across, c) Find your next piece before you finish getting the piece you are on in it's position (neomail me if you want tips on this), and d) RESTART OFTEN!!!!!! If you go over 90 seconds, get out of the game and restart. This will max out your winnings.
The Second part in getting a lot of money is to play both pokémon and kiko matching games. This can get you around 1,000 np per character. However, you should NOT start over on these- this will get you zero np for the game you are on.
Third game- Chiazilla. This is easy- move forward and hit mechazilla with your arm. Do not worry about his attacks, just get him to the wall press x like there's no tomorrow. These can get you around 2,000 np per character.
Fourth game- Techo says. Good luck with memorization. I suggest taking notes. About 500 np per character.
5th game- Codestones. I have only one suggestion- PRACTICE!!!!! One game can take forever, but can also get you around 3,000 np per character.
Sixth suggestion- Get lots of codestones (on the ground) and sell them for 1800 np per codestone. Not much, but they will be gone in a minute every time. For map peices that you don't need, sell for 1000 to 2,500 np. These have the same effect as codestones.
Seventh suggestion- Invest 4000 NP into stocks with a value of 4 (1000 shares). Stocks rarely go below 4, so you are will not lose any money.
Eighth Suggestion- Make your shop cheap. I know that it sounds like you won't make any money, but you will sell more items if you are the lowest on the wizard.
Ninth suggestion- Use the wheel of excitement (or boredom) to win loads of money.
10th suggestion- DON'T use the kiosk. It's a rip-off. But, of course, that's only my worthless suggestion, right?
11th suggestion- This game is great... You know.. it has prizes, neopoints, and it's EASY. Just point and shoot. I usually fire when the power hits around 52.
12th- Grundo's gym is also a nice way to make NP if you've been playing a long time (over 6,000 NP per day if you've played for a month).
13th- Now try playing "Chomby and the Fungus Balls" (wonderful name, eh?). Getting 800 points is easy if you can get past level 3, and you can sometimes get A MAGICAL GOLD CHOMBY PLUSHY, worth a whooping 70,000 NP!!!!! Smile, you've hit the jackpot. :)
14th- Pterattack- Easy game, and, although evven I could program better games, I must say it's VERY fun. Not much money, though, so play the hard mode to keep ahead of the game. :)
15th- Try Meerca chase... click in the top-right corner for the super-speed mode, and then play hard mode... It makes it MUCH easier. :)