[johnarryn]

A piece of advice I would offer is always attempt to diplomatically isolate your opponents... if you plan to attack nation X, make sure his other neighbors are either your friends, or indifferent to your conquest... this will help to make sure that your campaign can go forward without you having to worry about other nations getting involved.

Its also a good idea to quickly pick out who is the strongest of your rivals. Then you can start to support nations fighting that player, or even form a coalition against them...