I know this is like a lot of the other Neopets get rich quick guides out there but I am completely serious and this is very easy to do.
I have a couple of games that I play daily to get around 50,000 neopoints a day. Be warned, this takes hours to make (around 3 – 6-ish), so I suggest you take breaks in between, or go do something else in between hours.
If you were REALLY persistent, then you could probably make 100,000 neopoints in a day, plus with all the freebies.
Easy games to play that will make you around 20k in under an hour: