First step: Go immediately to TSR's home page and download Mythic Masters Magazine (if you haven't already done so).
Look over the Daily Deity for the Greco-Roman and Chinsungese pantheons. You will note a lot of superficial coverage and classification, with almost no hint of the myths actually involved.
Now, read the Daily Deities I wrote for the Norse and Kelltic pantheons. I have not done as complete a job as his Greco-Roman list, but they measure favorably and are probably more directly useful. Where needed, I have included some small amount of mythological reference.
The classification system is simple: ethos, tendancy, nature, and power.
The ethoi are: Sunlight, Moonlight, Balance, Shadowy Darkness, Gloomy Darkness, just as in the main Mythus book, where they are covered quite well.
The three tendencies are: Benign (generally beneficent in dealings with mortals), Malign (generally malevolent), or Agathocacological (either indifferent or exhibiting both strongly).
The three natures are: Ordered, Intermediate, and Chaotic.
The power levels are:
|Potency||Immortal Being or Supernatural creature|
|Quasi-deity||Powerful Supernatural being|
|Greatest||Extremely rare, usually a creator deity|
The gods should be classified along each axis, and inter-relations noted. If you are up to coding it in HTML, I recommend the approach taken in the Kelltic Daily Deity (although it is probably the weakest document I've produced for this so far).
While classifying, you will probably want to take notes on which deities play the largest role and are most likely to end up with a significant following. These will form the basis of the primary priesthood areas.
Feel free to e-mail me with questions about this, or suggestions.