I have added a few house rules to either make the game more playable or else give the setting a bit of flavor. They are as follows:
Character Creation: When making characters, you have 81 points to divide amongst your various ability scores as you wish. No starting score can be less than 3 or exceed 18 (before racial adjustments).
Hit Points: You receive maximum hit points per hit die at every level.
Action Point: Your character has an action point they can use each day that grants them an additional standard action per day or a +1d6 to any one d20 roll they make. At 8th level it increases to +2d6 and at 15th level to +3d6. They must declare they are using the bonus prior to rolling.
Super-Criticals: You can stack critical rolls on attacks if you roll a natural 20 on a confirmation (and only on a 20, regardless of the weapon's threat range). You then confirm the double-critical as normal, with additional rolls of natural 20 stacking more potential criticals. Every potential new critical confirms the previous one (i.e., if you threaten to crit and then roll a 20, you have confirmed the normal critical. Even if you fail to confirm the double-critical, you would still inflict the normal critical). For every additional critical you add to a super-critical, increase the weapon's multiplier by +1 (x2 on a longsword becomes x3 on a double-critical, x4 on a triple-critical, etc.).
Critical Failures: In addition to automatically failing an attack or skill check on a roll of 1, you threaten for a critical failure. You must "confirm" the failure by rolling again with the same bonuses and/or penalties as the original attack or check. If you fail the roll a second time, you screw up in a context-appropriate way. A critical failure in an attack might have you dropping your weapon or losing the rest of your attacks in the round. Critically failing to pick a lock might damage your locpicks.
Impossible Scenarios: Some rolls of 1 may not automatically fail, just as some rolls of 20 may not automatically succeed. If the total of your roll and any modifiers is at least 10 points away from failing (on a natural one) or succeeding (on a natural 20), then an additional d20 roll will be called for, which will be used to adjust the total. In the event of rolling a 1, you will take the new d20 roll and add it to your normal modifiers -20 for your total. If you rolled a 20, you will take the new d20 roll and add it to your current total.
Instant-Death Effects: One of the most annoying things about Pathfinder is all the effects that can one-shot even powerful characters. Thus, for PCs and certain powerful NPCs, they have a second-chance save against these sorts of effects. If you are struck by an instant-death effect and fail your save, you drop immediately to -1 hit points. The next round, you make a second save at the same DC. Failure means death, but success means you remain alive (but not stabilized) at -1 hit points. If an effect does not allow for a saving throw (such as a critical hit with a Vorpal blade or the power word: kill spell), you are treated as having automatically failed your initial save and then gain a save based on relevant factors (usually 10 + spell level or 1/2 character level + applicable ability score modifier).
Raising the Dead: Returning a dead character to life requires the direct intervention of a deity. Spells such as raise dead, resurrection, and true resurrection only bring the attention of the cleric's god to the situation. A character who is revived must make an accord with the reviving god--usually to perform a specific service such as slaying a monster or retrieving a lost artifact--and is only then restored to life. Failure to complete the task within the time limit set at the time of resurrection or death before the task is completed means that the character is dead permanently. This restriction does not apply to the spell breath of life, which actually keeps the soul from departing the dead body and returns it before the character truly passes on.