This past weekend was one of those winning games. A group of us got together and played on Friday night. There were seven people, so we teamed up having three groups of two and one person on their own. I was on a team with a friend who had never played Risk with other people, but had played it on an ipod touch plenty of times. We rocked.
My general strategy is to start in Africa. Some people like to go for Australia because it is easy to take, but I feel like it makes you too secluded. The only exit point is in Asia, and that is worthless for the first half of the game. Starting in Africa gives you the ability to take over South America.
Here is the coup de grĂ¢ce of this strategy: Once you have control of Africa and South America you are able to stop anyone else from getting bonuses in their continent. From South America you can hit North America. From Africa you can hit Europe and Asia, removing all of their rights to continent bonuses. If done correctly you are removing 17 potential reinforcements to your enemies. That's power that you can't get from any other position on the board.
One other interesting thing I've noticed is that the one time that I did lose I sat where I wasn't facing the normal top down view of a map of the world. Every other game I've played I've sat specifically so that I could look at the world like a map. It just makes more sense in my plans and schemes for world domination.