I was hoping someone would ask this. I've gotten every ending now.
Riches to Rags: Do drugs, never go to rehab or quit. The mob will kick you out.
The Big House: Never pay your taxes and try to do something big, or have heat over 100.
Suburbia: Become an FBI informant and don't kill Alexis.
No Escape: Do everything mediocre. Don't have high relationship with the other families and try to make peace, become a senator and fail, or try to share your story with the world.
Big Bang: Don't pay your tribute ever. The mob will kill you.
Hollywood: You need 90 perception and persuasion, and you can either go do stage performances, have a kid in the mob, or max out your relationship with someone in the mob. You can also get this by being with Jill or Jack.
Senator: You need seven bribed police, 100 police rep, or 100 FBI rep, and 100 citizen reputation. Also stay in politics the whole game and max your persuasion.
Bitter Boss: Have 100 relationship with Freddie, Dana, Daniel, or Jimmy, or a child in the mob. Take the option to make war in New Daria and you can either try and fail to convince the other families, or kill the Boss.
G-Man. Go to college, never do drugs, and turn FBI Informant at first chance. Assure the mob you're not the rat, and bring everyone down.
Boss of Bosses: This is tough. You need 100 Respect, and you can either kill all four bosses (possible) before the meeting or just whack them right there and then, which needs 95 fighting and 95 firearms.
Good Life: Don't kill any of the bosses. You need 80 reputation with all of them, which you can buy to make it easier. Technically, you only need 80+ rep with two families, as you can persuade and intimidate the other two. But that needs 90 persuasion AND intimidation, so you're better off buying them out.
Got Out: Don't pay the final tribute, or any. You need 80 perception to get the option to run, and 80 subterfuge to avoid being whacked.
The Hitman: Max firearms. You also need a silenced gun, which you can buy right after you get made, (costs $6000) sniper rifle, and 30 athletics and perception.