How we change what others think, feel, believe and do
Get other people to do as you ask by warning them about the risks of not complying.
Point out the dangers of their current path. Note the consequences of their actions, both in terms of likelihood and impact (both for them and for people they care about).
Be careful around Susan. She doesn't like you at the moment and could be unkind.
Watch where you are walking! It's rather slippery there.
I don't want to stop you, but if you do that it may get you into trouble at work.
Warning people about risks that they had not considered shows that you care about them. This will increase their trust in you as they realize you are on their side, and make it more like they will agree with future requests.
Warning can also be used as a subtle threat,
indicating that the risk is from you or something that you may control.
Warning is the 61st of the 64 compliance-gaining strategies described by Kellerman and Cole.
Kellermann, K. & Cole, T. (1994). Classifying compliance gaining messages: Taxonomic disorder and strategic confusion. Communication Theory, 1, 3-60