Bodyguard and detective are on the 'good' team with the civilians.
Gangster and crooked cop are bad guys.
So there are two teams.
The jailer is on the good team, but unlike the other special roles, he can be recruited. If the jailer dies, however, his role is reassigned. All the other special roles aren't reassigned.
AS THE DETECTIVE, YOU WANT TO INVESTIGATE THE BODYGUARD AND WORK TOGETHER HIM. IF YOU ARE THE DETECTIVE AND INVESTIGATE A CIVILIAN, YOU CAN'T REVEAL YOUR ROLE TO THAT PERSON BECAUSE THE GANGSTERS HAVE THE OPPORTUNITY TO RECRUIT ONE CIVILIAN DURING THE GAME.
Yup, each day a player is lynched. The one person with the majority of votes dies.
In addition to that, the gangsters will pick one target that they decide to whack (kill). They send their request to the narrator. So normally two players die each day.
The C's and G's win as a group. There's no purpose in backstabbing other G's. However, it has happened that the G's have sacrificed another G (I think it was Bezzy :D ) to make them look better.
The clever G's will often find behavior that will make the civilians look suspicious. Pointing out someone who voted on someone who turned out to be a civilian, who contradicted himself etc. However, as a G, it's obviously dangerous to put too much heat on civilians if they end up getting lynched so the rest will see you were wrong. So it's often dangerous for the G's to be push their agenda too much, but it's also suspicious to be too quiet. Ideally, you want to blend in as much as possible.
First: Go to Settings and General Settings. Turn invisible mode on. The gangsters will PM each other about their plans, so that way other people won't find you PM'ing the other.
When you're a civilian you want to have as much discussion as possible in the main thread. The purpose is to find out who the G's are, but also who the C's are. As much discussion and as many analyses as possible are good for the civilians. For that reason, the people who are suspiciously inactive and only show up when it's convenient (to vote, when the heat is on someone else), often looks suspicious. Generally, you'd want to play the same way whether you're a C or a G. But since you haven't played before, it's difficult to say for other people, if your behavior is suspicious or if it's just the way you play the game.