People are emotional, not rational. Appeal to their emotions first and then help to rationalize their decision. If you can get them to articulate how they feel about something, if you can get them to self actualize or self realize it, the idea will stick. If you tell them how to feel, they will know that the idea did not come from themselves and they will be more likely to dismiss it down the road. It’s just like the movie Inception – they have to feel like the idea originated from themselves.