If you want to consistently win games of One Night, it is crucial to uphold your credibility; and therefore you should lie more often.
Many players tell the truth to appear credible. That’s understandable, but this strategy is flawed. You can only tell the truth if you are a good guy, that is if you are on the villager’s team. If you are a werewolf, telling the truth will get you into trouble.
That’s why many players only lie when there are not on the villager’s team. But this strategy is also flawed, because most lies come out. Perhaps because the seer saw something, or the robber stole someone, or because the freemasons saw each other; players usually discover it if someone is lying. So if you are the type of player that only lies if you have a bad role, you are making it easy for the villagers to expose you. They only have to catch you lying to know for sure you are one of the bad guys. Otherwise you wouldn’t have lied.
This is why there is only one feasible strategy in One Night, and that is to always lie, even when you are on the villager’s team. Of course this doesn’t mean that you should claim to be a werewolf every time you are a villager. Your lies should be more subtle. For instance, you tell the truth about that you are the seer, but you lie about who you’ve seen. Or you say you have stolen someone, when you actually saw his card with your seer abilities. The trick is to maintain your credibility by speaking just enough truth, while subtly twisting the facts a little.
When the other players get used to you not being entirely honest, it is easier to talk yourself out of getting caught in a lie when you are a werewolf. You can say things like: “Yeah, I lied that I was the seer and I saw you. In fact I was the robber and I’ve stolen you”. Because the other players are used to you always making up little lies, they won’t immediately kill you because of it. By lying when you are on the good team, you allow yourself to lie when you are on the bad team.