
Chemlak |

A bit tricky without more detail on the ideas you already have, but here goes...
Don't design more than you have to - if the first adventure is going to be focused around the little frontier town of Frontiersville, you don't need stat blocks for the king who's a thousand miles away in Capitalcity. It would be nice to know what the king's name is, but you don't need more than that and perhaps some idea of what his subjects think of him. On the other hand, knowing who's who in Frontiersville might be essential.
Thoroughly design what you have to - if there are five dungeons within a day's ride of Frontiersville, design them all. Try to think about how the denizens interact. Players are a contrary lot and will often do something you don't expect, so having an idea of places they might randomly choose to visit is never a bad thing.
NPCs, lots of - design more NPCs than you think you'll need. These don't have to be full stat blocks, in many cases a name, level, description and list of personality traits will do, but it's helpful to be able to pull an NPC out of thin air.
Build conflict from the ground up - what if Baron Niceguy of Frontiersville is a long-term enemy of Count Nasty who is trying to take over the local area? Are Frontiersville's loggers starting to encroach on Elven lands? Who in the area doesn't want adventurers around the place making it safer? Why?
That should give you a good start.

Arizhel |

Start small, and let it grow.
If you have a good idea, let it grow. You probably want a vague map, a starting adventure plan, and a protagonist. I would pick what people live in your world, and the limits of magic right off, as well as a tech level/weapons availability. If you have concerns, start low, and let all of them grow.
It is much easier to find a forge that has figured out how to craft a curved blade, than to pull it out of the world once players have had access. Same with magic. If you hate summoned monsters, take them out now. Later if you want them in, let them in. Generally makes people happy when you give them new toys, and generally upsets them when you take away a shiny toy they are in love with. Start low, and you just make people happier, including yourself.

Mark Hoover |

To add to Arizhel's post - think as one of your players. Even if you don't have players yet, put yourself in the shoes of someone who would play your game.
Not only do they not need to know every detail of the world you're creating, but they want to be a part of it too. If the GM is just telling you everything static about the environment and it's details (tech level, availability of resources, etc) then you're just listening to that GM tell you a story.
Keep it interactive, mutable. Instead of saying "you walk into a bustling town square; you see a blacksmith, an armorer and a bookbinder's shop. In the distance you smell a tannery..." you might try "you walk into a bustling town square: what do you look for?" That way the players themselves help create the town layout around them.
Also...seconded to starting small. You'll be running online (I neve have) so I don't know if this will apply, but I suggest beginning with a single point of contact, a single settlement, a singular objective. Once you and your players feel fully invested in this first layer, add new ones.
Ex: you begin with the town of Erdanstadt; maybe it's part of a larger region/country/kingdom etc, maybe it's just a random wilderness settlement - at this point it's not important. Now just outside of Erdanstadt there is a ruined tower overgrown with weeds and vines; it has often been used by vagabonds and bandits alike as a temporary base but due to it's instability none have ever ascended into the upper levels of the place which are obscured by canopy. Local legend however tells that once the place was the home of a hermetic zealot who's religion fell outside the spectrum of acceptable. One day the man just simply wasn't there and the place was thought to be haunted. It is supected however, as no shrine has been found that clues might be found either above, or possibly below the ground floor.
Now give them a contact - someone who knows just enough beyond this set up to make the thing a tantalizing target. Maybe its a religious scholar, or someone just posing as one but secretly a heretic of the old order. Perhaps its just a penitent bandit; he was there with a crew and they drank themselves brave enough to ascend to the second story. What they saw there scared the man sober and left his hair streaked with gray. He escaped with his life...and a strange, cold-iron key in the shape of a ram's skull with coiling horns.
The point is - you've got a small locale with a narrow focus but one with plenty for wandering characters to explore.

IejirIsk |

And Again, I appreciate it all the help.
As far as online goes, it generally requires either more typing, or having the 'box text' already typed and copy paste, but allows you to do things privately to a specific char, ie: divination spells, whispering... i guess you could get 5/10 d20 rolls for hidden rolls in table top, and generally a program that will let you show the mat.

Arizhel |

One of the great things about PbP is time. If a players asks about X, even if you have never thought of that issue before, you have possibly a day or so to address the issue, instead of needing to recall, or invent, the solution to Issue X on the fly. You can use the time freedom to make a much more complex, layered and detailed world.

Mark Hoover |

Dang... I hate to purely rip... but, as a player, anyway, i kinda like that hook.
It's there to rip buddy. And what's more...think about what's written between the lines:
- Bandits are an issue in the wilds around Erdanstadt, yet the tower is not their permanent locale. Could there be some kind of thieve's guild in the area?
- The hermit might have belonged to a forbidden religion; is there a splinter cult in the town?
- If he was a hermit, how did people discover he was gone? Where did he go?
Now there's a ton of different ways to take it. You could go megadungeon on it and say that the hermit was actually an angelic being guarding the key to a teeming prison of evil below. He was destroyed or recalled but somehow the key remained safe...until falling into this simpleton's hands.
Just as easily you could go wilderness sandbox on it; the key merely opens a chest in a simple cellar but within the chest is a decent treasure and a map containing other locales of adventure for the PCs to journey to at their liesure.
Since the game's going online maybe its a mystery/intrigue thing: the heretic was the last possessor of the "Three Secrets of Skurne"; a lost order of monks whose knowledge could literally tear open the fabric of the universe. His order all went insane and blew themselves to smithereens except him and one other who sought to end the world. The hermit on thei other hand concealed himself here until something removed him from his solace. Now the party has to start answering these questions while also looking over their shoulder and watching who they trust - the nihilist is here in town slowly amassing a following to carry out the next armegeddon.
It's up to you but by starting with a humble seed a great garden of horror springs into being.

Mark Hoover |

Uhmm...AF and I have been around a couple campaigns. I can't speak for him directly (but I will anyway :) ) but he had messaged me once saying he'd look at my stuff if I needed a 2nd opinion. I'd offer the same; if you want another pair of eyes and some collaboration, I'm down. By way of a resume I've been GMing for about 30 years off and on for several different versions. I've got a lot of "collaborate with me" style threads on these boards and am always very greatful for the help; I'd love to return the favor.

IejirIsk |

https://docs.google.com/folder/d/0B8jWlyfCrL66M2lpTkJMLWdLTm8/edit?usp=shar ing
and i'd love to help, the combat is probably the easiest part for me... and this is what i've done at work last 2 weeks, is roam boards :P is why i got the idea of doing another online.
will warn, very bare bones atm. but, suggestions, ideas, critique always useful.

Master Of The Games |

My Arena Of The Gods PvP Campaign.
I will admit... This is possibly the worst Campaign I have ran...
I got hammered with problems. Still fighting Hexographer for Map Making.
Azaelas, The Myrmidon's Current Campaign.
Caedmon, The Hunter's Current Campaign.
Another PvP Campaign that I am somewhat a PC, under the Alias of Champion of Azaelas, in...

IejirIsk |

got maybe a 1/4 of the way done with a base ^_^... now, questions... again, back to never doing free game always been structured.
Mobs and XP... level appropriate, some challenge, how do i line everything up, how much exp, etc... >.>
have some thoughts for part of this, but not sure how to balance... preferably without overly fudgearific rolls.

Azaelas Fayth |

This Page contains most information you need.
I tend to just tell my players that most rolls will be open. So if the dice say they die then they die. No Fudging.