Red Ninja: End of Honor Hints for XBox
Also on: PlayStation 2
To get an easy stealth kill without worrying about sneaking, wait until the guards are walking away from you and then run after them, press attack when in range to execute a stealth kill. If you have enough speed each time the ranking you receive at the end will always be high.
Also on: PlayStation 2, check out those pages for more help with this game.