
lemeres |

Power Attack, Combat Reflexes, Lunge
Pushing assault too, as a companion to lunge.
Both lunge and pushing assault work together to keep enemies in the sweet spot 15' away, where enemies have to make actual move actions and eat AoOs in order to reach you.
Those 4 feats are basically what you need to 'master' a reach build.

Tindalen |
Required: power attack, Combat reflexes
Crit Phisher Options: exotic weapon proficiency(fauchard), improved critical, and one of the following
Trip Maneuver Options: Combat Expertise, improved trip, greater trip, Tripping Strike
Reposition Maneuver Options: Improved reposition, greater reposition, quick reposition, tactical reposition, Wings of the Androsphinx

ArtlessKnave |

I had once created a Human Paladin that focused on tripping with a reach weapon. Mind you a Human Fighter would do this better because of the number of feats you get. (We needed a Paladin at the time) Here are the benefits:
I used the Guisarme and went with the Heirloom Weapon Trait for the +2 bonus to CMB for trip attacks. I then picked up combat expertise, improved trip (another +2), combat reflexes, Fury's Fall (add dex to CMB too). You can keep going with the fighter into weapon focus/specialization, cleave etc.
Basically you can trip anyone because your CMB for trip is stupidly high, they have reduced AC against your next attacks when prone, if they stand they provoke in which you can choose to make another trip attack to keep them on the ground. Since you have reach you don't provoke even if you don't have improved trip and if you fail, you can easily drop the weapon without them getting a chance to trip you back.

GM 7thGate |

This is the build I'm currently running through Rise of the Runelords, essentially. I'm a human fighter who started with Hierloom Weapon, Combat Reflexes, Improved Trip and Combat Reflexes so started out at +9 to trip at level 1. It does make certain fights stupidly easy (I'm at level 7 now; essentially anything with two legs, large size or smaller that relies on melee attacks might as well not even be in the fight).
One note though, because Attacks of Opportunity preempt the action that triggered them, they're still on the ground when then try and stand up from trip. The good news is that they're prone, so you're at +4 to hit essentially. The bad news is that you can't use that AOO to trip them to prevent them from standing.
You can, however, use that AOO to disarm them. There have been a couple of fights vs. melee opponents where they just get tripped, disarmed on stand, tripped on picking up their weapon, repeat until dead from normal attacks mixed in with the AOOs.

lemeres |

GM 7thGate wrote:The bad news is that you can't use that AOO to trip them to prevent them from standing.Do you have a page reference for that? I am curious as we must have overlooked something in the rules.
It is the basics of AoOs- you get your AoO before the AoO drawing action is actually done.
If it didn't work this way, then it would be impossible to stop spell casters by getting in their face and punching them when they start hand wiggling (since the hand wiggling would be done prior to the point where you do the AoO, and the damage wouldn't get applied to the concentration check)
The order of events for spell casting AoOs would be"
Begins to hand wiggle-> face punching-> Concentration check (10+spell level+damage taken)-> spell gets cast if the check succeeds.
So the order of events of getting up would be
Begins to get up-> Kick in the gut-> finishes getting up.
If you could chain trip, it would need to be in this order:
Begins to get up-> Gets up-> you then trip him again
But that would means spells would be
Begins hand wiggle-> Finishes spell (no damage taken before finishing spell- at best, concentration check is 10+spell elvel)-> Face punching...if you weren't blown away by the spell.

GM 7thGate |

There was a big thread about it over here: http://paizo.com/threads/rzs2l0rq&page=3?TripLocking-Doesnt-Work-Offici al-Ruling-or-Not
The AOO rules are not the most clearly written in that they say they "Interrupt" whatever it is you're doing. That is not super clear on what the status of the opponent is when you take your AOO. I believe the reason you can't trip someone who is provoking from standing up is the same reason why you can make a melee attack against someone leaving a threatened square without being able to reach the square they're moving too; you get the AOO, then the thing happens (if it still can), so they are still prone/in the square next to you when the AOO provokes in the two cases.

Gwen Smith |

Reach Weapon + Readied Action is a great strategy. Ready an action to hit them when they come within reach. Then they provoke an AoO when they continue walking. If you have someone tripped, ready an action to trip them as soon as they stand up. Take your AoO normally as they try to stand up, then when they successfully do stand up, your readied action goes off. (Check with your GM first: some GMs won't let you take AoOs if you have a readied action.)
If you have Greater Trip, them falling prone provokes, so you get an AoO when they fall and another AoO when they stand up.