Restocking is how I earn a ton of my neopoints,
It's when you buy cheap items from shops and resell them.
Here are some guides that I've used:
http://neonewsnow.com/neopets_guides/restockingtips.htm
http://www.thedailyneopets.com/articles/restocking/
http://www.neopets.com/~xo_BabyCakes
Post some of your own guides, and where you like to restock!
Personally, I restock at the furniture shop. I know that shop backwards and forwards