I'm not sure if this will help, but I'll just mention a couple of thoughts regarding expansion.
Whenever I expand I'm always looking for choke points that I can use to build a wall around my territories. I can always go back and take other indie provinces inside that wall later. At the same time I try to be reasonable - if you get greedy and box people in and they have no direction in which to expand they have little to lose by attacking you. By and large I think early wars are bad for both parties. Assuming equal skill, you will drain each other's strength while other nations build up.
But in the end this is a war game and sometimes two parties don't see eye-to-eye and end up fighting sooner rather than later (eventually *everyone* fights - well, unless late game micro beats them down and they call it quits
). As far as having a friendly game I would just request that it not get personal. It can help if you try to keep in character and attack the nation, not the player.