"All that is necessary for the triumph of evil is that good men do nothing."
-Edmund Burke
Imagine the following game: every townie stays silent during the day. No one ever speaks. Not the sheriff, not the investigator, not a mafia member pretending to be a citizen. Who will win? The mafia of course.
Now imagine this game: on the first day, every townie states his role and what action he performed on whom. The same for the next day, the same for the next. While mafia might very well lie, with so much information, their deceptions will very quickly be discovered. Who will win? The town of course.
For most standard variants, town is the hardest and most active of the three teams to play. If town is silent, they lose. If town lacks information, they lose. If town is deceived, they lose. If town does nothing, they lose.
Overall strategy
Except for variants including lots of neutral killers or vigilantes, the town's only chance of achieving victory is through the lynch. Lynches require intelligence and, above all, information. In The Adventure of the Copper Beeches, Sherlock Holmes said, "Data data data! I can't make bricks without clay." The data in Mafia comes in many objective forms: the graveyard, innocent/guilty voting records, the speed with which lynches are carried out, etc.
Unfortunately, this hard data only goes so far. Much of the time you must rely on subjective, hard-to-interpret data: PMs, last wills, sheriffs/investigator claims, other false/true claims and accusations, the things people say and the way they say them. As a townie, you should be aware of the following DOs and DONTs:
- DON'T be silent. Silent people are not to be trusted. Towns thrive on information and discussion - if a person is silent it's often because he's afraid of being caught in a lie.
- DON'T make claims without information or extensive reasoning. If someone claims to be sheriff, but you're a doctor who nevertheless has a gut instinct he/she is lying, DO NOT claim, "He's mafia!" If that sheriff turns out to be real, you just completely discredited yourself and probably earned a lynch.
- If you do get lynched and you're an innocent, DON'T troll or be antagonistic in your defense. "Random lynches" are often attempts to force information from players - most good townies will vote you innocent if you're civil.
- DO state your role in your lynch defense. In most townies minds, failure to state your role and provide supporting information as to what you've done with that role is an automatic guilty sentence.
- DO be aware of the roles in play and how those roles actually work. If a sheriff claims that a person "works with knives" then that person is lying (investigators discover that information). Understand that an invest's "owns many guns" could be either vigilante or mafioso. Understand that if a GF has night immunity and, as a vigi you shoot him, it'll declare his immunity, which means you have, in fact, discovered the GF. Etc, etc.
Now, to go on to specific roles and how to play them...