I think the GM has to know exactly what they want stylistically out of their e-fed, what goals they're going for as far as a thematic type of federation, be it hardcore, old school, shoot, or something completely different. If they don't have something concrete and eye-catching enough for people to want to be a part of it, or at least understand what's expected of them and an idea as to whether they'll like how things will run, then it's already dead in the water.
After you get a roster, there's a matter of keeping people and sort of building a community around a small hobby project. By far, EAW's probably done that better than any fed I've ever been in when it comes to things being lighthearted and non-toxic. Maybe it's because we all have the personality of an asshole and accept the barbs thrown at us mixed with the mutual admiration of one another's work and the willingness to actually help those who ask for it. Either way, keeping this sort of stasis in an e-fed with three massive and distinct roster splits is pretty incredible. I've seen other feds cannibalize with mergers, much less brands. So yeah, weed out the nut jobs and softies, and you have a fairly stable fed base.
After that, it's more or less up to the GM to keep the results in on a moderately reasonable deadline and the fedder's to keep the rp's coming in on a steady flow. I'd say avoid political slant and hierarchy, but I think that's pretty impossible with fedding, especially in the case of a community like this when fairly renowned people from other e-feds that belong to the same fed circle come in with a reputation that can't be denied. Case in point, people had a problem with HBB jumping ahead in line a few months back when he came in. I didn't. Most rpers who know him don't either. It's the equivalent of Shawn Michaels (pardon my somewhat literal analogy) jumping to another company and getting pushed to the top of the card. Why wouldn't any sane person do that?
But yeah, have a compelling idea, build a roster, keep the status quo, and be reasonable when it comes to booking decisions. That's what e-feds are made out of. That, and a list of 10 rules that always ends with "Have Fun!" After reading Vince's commentary manifesto, it makes me wonder if he feds...