I find it best when the GM is fair and somewhat strict. Give people 24 hour notice before moves are due and allow players the right to emergency postponements, but once the deadline passes and they are still silent, then it is imperative you apply the NMR (no moves received) so that the game keeps moving. Generally two consecutive NMR's merits removal of the offending player.
Also, you don't need to be an expert in adjudication if you use the RealPolitik program - it also gives wonderful maps. In my game, I would always insert a hyperlink to the website hosting the game in adjudication e-mails to the players, thus encouraging them to view the thread and make public comments, which generally makes the game more intriguing not only for those playing, but for casual observers as well.
If you need more detailed info, PM or e-mail me and I will go over specifics.