Okay so, playing Mafia is difficult when there are a lot of TI roles so they need a way to control the information or prevent players from finding them.
Generally, players claim based on their investigated results, for example, a Godfather is most likely going to claim Bodyguard to appeal to the investigator, and a Mafioso would claim vigilante. This can be a huge problem for the mafia though since it's not a really good claim. Claiming these roles means they can't really push people without being seen as suspicious. Especially when you're pushing someone who has massively contributed for the town. Claiming vigilante would mean you're forced to shoot someone and then claim that they're immune, but town probably wouldn't believe you and then you get lynched or executed. A Godfather claiming Bodyguard will also probably backfire because there's always gonna be a Town Protective counterclaim, and then they're gonna just gonna hang both claims which isn't a good trade off for the Mafia. There's always a flaw when mafia roles claim to match investigative results because well, it's obvious.
Honestly, the investigator is probably the most powerful Town Investigative role(The Lookout is also quite good). But this role is also pretty difficult to play as or claim as because town will accuse you of being consigliere if you don't contribute a lot for the town. So this is a pretty tough option for mafia to claim.
Now, the Mafia needs to kill all Town while staying alive. So they will usually just stay quiet until they kill enough people. This however, is a horrible strategy because they become sitting ducks until Jailor or other Town Investigatives find them
Here's the real smart boi strat: CLAIM INVESTIGATOR OR SHERIFF! This is probably one of the best things you can do. But it still takes a lot of coordination with your teammates and you need to back each other off. Remember, the Mafia usually has 3 or 4 members, so that's like a quarter of the Town's votes. Mob mentality is extremely powerful tool for the Mafia to use. Usually in early game, town will literally accuse each other so Mafia should stay low until Day 3 or 4. Then, when town is low on numbers, the entire mafia should ALL come out as Sheriffs or Lookouts and work together to accuse. The mafioso or Godfather should claim sheriff and accuse one guy, then have the Random Mafias claim Lookout and post a fake will. This will 100% guarantee their target being lynched. Then the next night, assuming the Town Protective is dead, the mafia should kill the jailor or other Town Killing roles and then it's all smooth sailing from then.