How we change what others think, feel, believe and do
When people experience a threat to a valued element of their self-concept, then become highly motivated to seek some sort of social recognition of that identity.
Gollwitzer took some promising dancers and asked half to write about their best instructor and half about their worst instructor. Later they were asked for a date when they could perform in public. Those who had been reminded of their worst instructor (and hence had their self-concept threatened) offered dates on average two weeks before the non-threatened dancers.
If I fail a test, I will actively seek out someone to tell me I am still clever, thus restoring my sense of self as an intelligent person, or maybe pick an argument with someone to show I can still outsmart others.
Arrange for people to be threatened some one else (or just watch out for it to happen naturally). Then gain trust by being there to stroke and support their self-image.
You can also challenge a person's capability in something and they will actively seek to disprove you (and re-prove to themselves).
Beware of flatterers. They may want something of you.