Beginning the campaign
There are few things more exciting and energizing for me as the idea of a new campaign. A new world about to be shaped and spun and sculpted however you like, it's a sense of clarity and possibility. So, how does a prospective DM make the most use out of such a exhilarating situation? I'll show you how I do it. I won't show you how you have to do it, or how "a good DM" does it. I'll show you my methods, take what you like, leave what you don't.
For me, the first step is Talking to your players. Now, I realize that not all gaming groups work the same way, and some DM's don't have the option of consulting their players first, but whenever possible I highly advise finding out who is playing and what they want to play. As a prime example of this, I was talking with my players after a session and asking them what they wanted to do for a long running campaign. Their answer was a little surprising "I want something gritty and low level, that stays low level for a long time" This came out of my longest running player and best friend, a guy who has been with me for a level 75 campaign, a level 20 gestalt game, and has generally relished playing spellcasters and very high powered builds. Needless to say I was shocked. But with that idea present I asked the others what they thought. It seemed the feeling was fairly mutual, but another player added in "I think it'd be cool to start off as farmers, or maybe even orphans and work our way UP to farmers". Now there's an idea. And a third mentioned having really loved one of the campaign settings I'd talked about and shown them for a one-shot we did a while back, which was met with a round of head nodding.
From a little bit of conversation I already had an idea formed. I remembered Ultimate Campaign had rules for building a business and home from scratch, and my players and I were already familiar with a Rules-set called Epic 6. I recommended using both sources and the players seemed very excited, even to the point of also asking if we could use the Slow levelling up progression, which was fine with me. After some thought the idea also came up that eventually in the campaign they'd want to be able to exceed 6th level and use the Mythic rules from Mythic Adventures and everyone was very pleased with this idea. Once the ball started rolling everyone immediately began coming up with piles of character concepts and stories and it exploded from there.
By the time the conversation and the session was over I knew my players wanted an Epic 6 game with a slow progression that would see them start off very small, weak, and poor, and then gradually grow, building a farm and a business, and then somehow unleash mythic power and the ability to exceed 6th level. And all of this was to take place in a setting I'd already started a while back that just needed some modifying. I hear from other DM's all the time "I don't know what I'd run" and I think any of them given a list of details like I wound up with could be off to the races in no time. All it takes is a little communication.