People thought I was a multi because I got good right away.

I found people who were good players and watched how they played, looked at their old games etc
Not because I wanted to get better but because it genuinely interested me

So yeah Renaldo is right. The biggest thing is that universal "scumtells" are often not legit~

Search "Crypto's Guide" in the epicmafia forums

Find players that are better than you and see how they play. When you die, watch games in the GY and try to play as if you're still alive. When you see who mafia actually is, read them and try to see if you can find their tells or what makes them sound disingenuine.

Those are some quick tips. There's no systematic way to get better. It's all about effort in individual games and adapting to the situation