Keep hammering them with facts, details, allegations, baseless claims, even slivers of truth. The average person doesn't have the time, interest, or capabilities to dig through all of those claims, and will eventually settle on consuming the facts they want to hear. Keep em too confused to do anything except what feels right to their gut.
Unsurprisingly, this was pioneered by the Soviets, and heavily used by the Russians, both via foreign agit-prop, but also heavily on their domestic audience.
See also: The Russian "Firehose of Falsehood" Propaganda Model https://www.rand.org/pubs/perspectives/PE198.html