Here are some things to think about when generating your pantheon and creation story:
1. If there is a good aligned god, there should be an evil aligned god. You can be symmetrical and do a on-for-one type layout; one major evil god for each major good god, as well with minors. Or you can be non-symmetric in either direction. It really comes down to your preference.
2. Depending upon who you want the bad-guys in your campaign to be, you can make preliminary decisions about the gods. For example, you may have a major deity that is evil and is part of the creation myth, but you may assign a minor deity to the undead, and a different minor deity to aberrations, and a different minor deity to natural beasts, and a different minor deity to the goblins. All of the minor deities may ‘report’ to the major deity like generals in a war, or they may be stand alone gods, but just not have major deity status (maybe there is an attempted coup going on in the abyss, with a minor god trying to rally the troops to mutiny against the current evil god and take his major position).
Did you see what I did there? I thought up, on the spot, a possible story arc background reason why there is suddenly an increase in goblin related violence in the town in which the PCs currently reside. Maybe the minor god, Trat, is gathering a large goblin army to wreak havoc on the world and gather slaves so that he can lead a massive goblin army into the abyss and battle with the major evil god. Get into the habit of connecting things like this – and then writing them down as soon as you think of them. It doesn’t matter if you never use the idea, it’s there to be used when you need it and it may eventually see its time come. If you don’t write it down, you may never remember it again, and it may have been a kick-ass idea.
3. You are not obligated to create an entire, 100% fleshed out pantheon on day one. In fact, you shouldn’t do this. You should let things that happen in the game world affect the pantheon, and vice-versa. Write only a small introduction to the pantheon and the creation of the world so that they players can pick who to worship (and if necessary, you can change the names of feats that apply to deities to be appropriate to your campaign). When the players run into a death cult that worships Haggaba the Slayer, they can use their Religion skill (or possibly arcana or nature) to find out what they know about this deity. You can make it up on the spot if you already have a general outline in your mind or on paper.
Usually I have a paragraph or so on the major gods and a sentence or two about the minor gods. They all include alignment and what type of mortal worships the god, as well as any relation to other gods. In case you didn’t know, the gods of ancient times were relatively incestuous and promiscuous (with mortals and immortals alike, though the mortal usually got the raw end of the stick) and that sometimes makes for some rather interesting family relationships. It also opens the possibility of having children of the mating between a god and a mortal play in a campaign – this gets interesting at higher levels.
4. After the initial outlay of basic pantheon information, you should get in the habit of fleshing out the universe in little chunks. I tend to work in little bursts of productivity. I may sit down and write up a few lines of an idea that occurred to me and that may lead to a couple of hours of frantically trying to capture all of my ideas before they wink out of existence, but when I’m done I usually have a large amount of things to work through and flesh out, little by little, over the next few days.
The biggest thing is to have a vision of your campaign and make sure that, however the creation process goes, you are happy with the result.
~DM Samuel