This method sounds dangerous.
"I should kill him" gets 10,200 mentions on a Google search.
"I shouldn't kill him" gets only 29 mentions.
Coin Flip Decision Making, with Regret Option
My own favorite method, which I used to choose between Northwestern and Michigan for grad school, involved flipping a coin. The flip came up heads, which meant Northwestern. I realized I wished it had come up tails -- so I went to Michigan.
If you flip and regret the choice, reverse yourself. If you flip and don't regret the choice, stay with the flip choice.
This method works best for double approach or double approach-avoidance decisions which have substantial uncertainty which can't be resolved. In this case, I only know that Michigan was the right choice for me because I met my wife there and she might read this blog.
[Thanks to Ezra Klein and Marginal Revolution.]