In the upper right, there is a list of the characters that might appear in the round and you can right click to learn how their abilities work. Some like Wretch (always good so never kill, but seen as a truthful but evil minion by truthful characters) can cause unexpected behavior.
The rest is logic.
If you have Poisoner (+1 Corrupted villager adjacent to Evil) and Baa (Don’t know which outcast will be in play), and a choice between Drunk and Wretch for the one outcast and no wretch appears on flip, then you expect 4 total lies - one drunk, one corrupt, and 2 evils. At least two liars have to be adjacent. Then you plot out possible scenarios that would make the board consistent with 4 liars (if X is a lying evil, this guy must also be a liar).
Then you kill someone suspicious (unless you kill a bombardier or you are in a Lilis round, you get a “free” kill) and find out if you logicked wisely. If you were wrong, there’s a good chance you can use the new information (dead cards reveal if they were truthful or corrupt) to pivot into the correct solution, especially if you didn’t tap all the character abilities.
Also you can use dead character abilities, even if they were evil, which helps.