Easy Way

Walk into a shop and grab an item, (u need the sword, go figure) run around the shopkeeper and when he's looking the opposite way of the door, run out! If you miss timed it, you'll have to restart :3 oh yeah, the next time you walk in the shop, all the items are gone and the shopkeeper will say: "I mean it when you'll pay, now you'll pay the ULTAMATE price!" and he kills you with a ray beam...

Good Timing Way
This way, you'll have to pay (but you get to keep you're ruppes!)
1. Have right amount of ruppees for item
2. Tell the shopkeeper and pay for the item
3. Before you ruppees are disapearing, quickly press R L Start Select! Save and quit
4. You'll have your ruppees back AND the item ifi you timed it right
Enjoy your stealing!

Make sure you have bow-wow (the thing that looks like chain chomp).
Stand about 3 paces max away from an enemy.
When they move bow-wow will eat them and hey presto you killed an enemy without moving!