but seriously, folks...
IMC, I do this:
Every critter, including NPCs and PCs, gets some bonus HP based on race and size.
PCs & NPCs:
Gnomes: 2 HP
Halflings: 4 HP
Elves & other Fey: 6 HP
Humans, Half-Elves, Dwarves & Half-Orcs: 8 HP
ECL +1 Outsiders (Aasimar & Tieflings): 10 HP
General Monsters:
Fey: 6 HP
Outsiders & Elementals: 8 HP
Oozes: per size, in MM
Others: per size:
- Diminuative: 1 HP
- Tiny: 2 HP
- Small: 4 HP
- Medium: 8 HP
- Large: 16 HP
- Huge: 32 HP
... etc.
Then, roll dice for your class level(s) normally. This means that a 1st level Halfling Fighter will probably not be as tough as a 1st level Human Wizard, but it also means that a housecat can't kill a level 1 human easily.
For the DM, you can reduce the HD of your larger monsters without lowering their threat. This means that an ogre can be a CR 2 threat without needing more than two "real" HD -- which makes him vulnerable to Sleep spells and such, unless he has some class levels.
-- Nifft