So there's 2 runs of games that I think will be season-defining - from now until the New Year is the first:
Everton v Liverpool Sat 23 Nov - Last Season D
Hull v Liverpool Sun 1 Dec - Last Season D
Liverpool v Norwich Wed 4 Dec - Last Season W
Liverpool v West Ham Sat 7 Dec - Last Season W
Tottenham v Liverpool Sun 15 Dec - Last Season L
Liverpool v Cardiff Sat 21 Dec - Last Season W
Man City v Liverpool Thu 26 Dec - Last Season D
Chelsea v Liverpool Sun 29 Dec - Last Season D
Last Season = 13 points
It's a run of 8 games, with 4 we'd be expected to win (though it doesn't always work like that) and 4 that will be amongst our toughest all season. It's 24 points up for grabs, we should be hoping for something like 15-16 points from that run of games to keep the pace, but it'd be no disaster if it were a few less than that. As others have said there's a lot more points in beating the teams well below us than the teams around us.
This run of 8 games also takes us to exactly halfway through the season - if we're still averaging something like 2 points a game at this point then we're in running for the title, nevermind top 4. It's worth remembering that once this run of games is over most of our tough away trips are over for the season. When the last 2 do come, they come in the March/April run of games which is the other that I think will define our season:
Southampton v Liverpool Sat 1 Mar - Last Season L
Liverpool v Sunderland Sat 8 Mar - Last Season W
Man Utd v Liverpool Sat 15 Mar - Last Season L
Cardiff v Liverpool Sat 22 Mar - Last Season W
Liverpool v Tottenham Sat 29 Mar - Last Season W
West Ham v Liverpool Sat 5 Apr - Last Season W
Liverpool v Man City Sat 12 Apr - Last Season D
Norwich v Liverpool Sat 19 Apr - Last Season W
Liverpool v Chelsea Sat 26 Apr - Last Season D
Last Season = 17 points
That's 9 games with 5 of them against teams in and around us. The difference is that as much as I think Southampton are an improving side, certainties I would think to finish top half, they have a similar problem to Tottenham with a lack of strikers scoring goals. They will continue to grind out results and going to St. Mary's will be tough as we saw last year, but I'd expect them to be 7th by the time that fixture rolls around. The other thing that's different is that where in the other run of games all the toughest games are away, in this run we have 3 at home which could be vital. Again, we should be aiming for about 17/18 points from that particular run if we want to be in with a shout of the title. For top 4, we can probably afford to drop points in a few more places.
Encouragingly, if you look at last season, we don't need a massive improvement with either run to meet those targets, and if we do meet both it'll be very hard to see us finishing below third.