Most decisions aren't A or B, they're I want A, but B is much safer/easier/etc. So the coin flip method (you'll make up your mind while it is in the air) doesn't help since you already know what you want. Pros and cons lists don't help since you already know them. Probability multiplied by reward doesn't help much, since you'll really only make the decision once, not continuously.

The only sure fire thing I've found helps is you imagine the realistic worst possible case scenario if you decide on doing thing A (the thing you really want) and if you can live with that, do thing A.