1. Suff to do every day
Play the fruit machine in the lost desert. You can win heaps of loot!
Visit Coltzans shrine in the lost desert. Great junk to be found and you can raise your pets stats too!
Visit the garage sale on terror mountain. Things are so cheap there! You can sell the stuff you buy for lots n lots
Get an omelette from the giant omemlette in Tyrannia. These can feed three pets for free!
Visit the snowager. Many random items can be found.

2. Play Games!
Games like kiko match can win you heaps in a day. Poogle solitaire is good too if you know the answers! Find a game you're good at and you can live off it.
The poogle solitaire answaers are-
29-17, 22-24, 17-29, 31-23, 32-24, 24-22, 26-24, 33-25, 24-26, 21-23, 16-28, 14-16, 9-23, 28-16, 7-9, 27-25, 18-30, 20-18, 11-25, 30-18, 13-11, 10-12, 3-11, 18-6, 1-3, 3-11, 12-10, 5-17, 17-15, 4-16, 15-17

3. Open a shop
This one's so glaringly obvious that I almost didn't put it in. Open up a shop, ppl! It's possibly the best way to earn NP. Search for bargains on the shop wizard and then sell! Don't sell your items too cheap or you won't make a profit, but don't price them ridiculously high either. If you find items as random events you can sell them for sometimes huge profits, I once found a clloud PB and sold it for 19000NP!