The first round of play is often the most important. A great way to mix up the game is to change the starting units and thier locations. Two variants:
Before the first round, each country can trade in three units for thier cash value and the nspend that cash on whatever they want, and put those units where ever they want. Most often, people will cash in expensive units like battleships, bombers, or industrial complexes and buy extra tanks, fighters, or whatever it is they want. This has awesome potential to change the start of the game.
Version two, you start with all the same units, but can re-arrange thier starting locations around your territories. Again, all kinds of different starting strategies can be found.
In both of the above cases, players must work out what they 're buying and where they’re putting things on the map WITHOUT ACTUALLY DOING IT. You write it down on paper, then when everyone has done it you reveal your plans to the rest of the players. This ensures you can’t tailor your plans to what other people are doing, and it makes people awfully surprised to see what thier enemies are plotting.