I feel quite special you asked me for hints, because I don’t really have a special area for anything. Restocking always makes good neopoints, especially on half price day…but that’s just something you have to learn. Buy only the stocks at 15np and wait for 100%-200% profit. Refresh the trading post looking for good deals, and if you have the patience, buy hard to sells at ridiculously low prices, not “just 200k off lowest post price” – look for buyable unbuyables and the likes.
I think, but I’m more into all aspects of Neopets, I like to gamble a lot with Brucey B slots. The Scorchy Slots were just too slow for me, and i have about 150k-200k invested in the stock market. I’m a little bit of everything, not really focused on neopoints because I can’t find the items I need to spend the NP on.