If a choice involves a definite action and the consequences are either good for positive motivations or bad for negative ones, then there shouldn't be a need for any warnings. If there is no clear right or wrong choice, then any hints should be not be obvious (except maybe at the start of the game).
For choices made through dialog options, the final remarks that indicate a choice should be phrased clearly. If you say something that sounds non-committal to get out of a conversation (ie to save the game before proceeding) that shouldn't make the choice for you.
Elgi: [color:"orange"]If the choice is very obvious, it isn't fun anymore for me.[/color]
Same goes for the consequences. If there are warnings for everything you might as well play the game after reading ahead in a walkthrough.
