Depends on the spoil type you're playing with. If it's Escalating, I'll echo what anonymus said and check out the SoC Training Academy
here. No Spoils/Flat Rate's a different animal, but once you play a few SoC games, you'll develop a good strategy for it.
On Escalating, the idea is to build up several good-sized stacks around the board in spots that attack 5 or 6 other territories. You should have one in each region. For Asia, Dubai is good, as is Moscow and Delhi. In North America, Chicago or Vancouver are nice. It's not as important to have a strong stack in Europe or Africa, but I like Istanbul or Dakar for a third stack. Hong Kong is good, too, especially if you hold Istanbul.
It can be good to have a small stack in South America and/or Oceania, as well, if someone isn't trying to conquer that continent.
There's an official strategy guide up in this forum (see the
Official Guides up top), so check that out, and check out the SoC's
First Four Moves, too, found in the
SoC Guide in the Training Grounds. Good luck, and PM me if you have further questions or if you're interested in training.