The following segment was written in response to MavrickWeirdo's comment.
My advancement rules were
originally written for a setting with no dwarves, elves, gnomes, half-elves, half-orcs, or halflings. But that's just
my setting... how can I make these rules work for other settings as well?
The first thing, of course, is to get me some aging rules for all of the races. This is pretty easy, actually: just multiply all human years by the race's maximum age (I rounded closest), divided by the human maximum age. Then use my modified human aging rules with the same multiplier.
Thus:
Code:
[COLOR=coral]
Race Max Mult Adult +/-1 abilities Aging Roll
Dwarf 450 x4 60 per 20 over 100 per 4 over 120
Elf 750 x7 105 per 35 over 185 per 7 over 225
Gnome 500 x5 75 per 25 over 125 per 5 over 150
Half-Elf 185 x2 30 per 10 over 50 per 2 over 60
Half-Orc 80 x1 15 per 5 over 25 per 1 over 30
Halfling 200 x2 30 per 10 over 50 per 2 over 60
Human 110 x1 15 per 5 over 25 per 1 over 30
[/COLOR]
Vaguely boring, sure, but it gets the job done and keeps it out of the way. I'd love to see some rules for elves "fading" instead of "aging", but it's not really necessary.
Once that's done, there is a question about your setting that has to be answered: Do you want the long-lived races to be
slow learners or do you want to deal with the effects of them achieving higher levels? Note that you need to answer this question no matter what, if you have long-lived races who gain experience points.
Slow Learners: Easy, just multiply years and months (for non-adventurous jobs) by their age multiplier for purposes of CR of scenarios. Thus, an elf has to farm for 7 years before gaining the XP for a CR 2 farming scenario. If you are using MavrickWeirdo's simpler rules, an elf gains 1 XP every 7 days (elves "learn something new every week"

).
Longevity Means Experience: This is more difficult, but can be more rewarding in terms of the richness and believability of your setting. Here are some possible approaches to the issue:
Reign of Flowers
Elves rule the world. "Young" elves (between age 105 and 200) are typically below 10th level, but any elf old enough to have started aging is more skilled than all but the most legendary of humans. In order to maintain their political superiority, there will need to be at least one "aged" elf per 10-40 humans (depending on level), and they will need to be
ruthless when it comes to human heroes, rebellions and whatnot.
So Few Left
Once, perhaps, elves ruled the world. But today, there are simply too few of them to do so. There are a hundred or more humans per elf, and that's not even counting the upstart dwarves and gnomes, or the barbaric orcs and goblinoids. Sure, individual elves are ancient and powerful, but an uppity elf will likely get swarmed by a kingdom of humans... and killing all of them is likely beyond him.
Summerlands
The elves are powerful, but are concerned with events in their own realms. This is much how the Epic Levels Handbook seems to suggest Epic NPCs are handled, and it works okay. Vaguely Tolkien. This is also sort of how I'm handling their equivalent-in-spirit in my own Europ setting.
Guiding Hands
The elves live so long because they've largely conquered their own gaps in worldly understanding. Now they provide (benevolently) a guiding hand to those who ask it, and otherwise leave the world alone.
Humans Don't Organize, Mr. Silverleaf
There are not
quite enough elves to maintain a ruthless grip over the world, and humans have organized a thorough resistance. You could have Swiss-like dwarves who are curious which side will win, halfling guerillas helping the humans secretly, and elven traitors (who may simply be agents for the enemy). This will also tend to result in higher average levels for humans, because of their constant state of warring.