When playing Europa Universalis II, keep in mind that there is an unlimited number of things that can go horribly awry and take you nation down a peg or two. Your national stability should be kept as high as possible (+3). This affects how much income you receive, and how happy your subjects are. If you become too unstable (-3) you will need to drop everything and invest heavily in stability or else you run the risk of having your government collapse, a civil war breaking out, or your enemies seizing the opportunity to attack you (or all three). Stability is the most important part of your country, make sure to stay stable and you should be alright.

The cost for improving your stability depends of how your country is arranged. If you have a very decentralized nation, stability will be cheaper to improve, but technology will cost more. If you en serf your people they will be more likely to believe anything you say, but free peasants will be more likely to join your army and fight harder to protect their freedoms. Developing a strong nobility establishes a tradition of sending sons to the calvary and reduces the cost of mounted soldiers, but if you stress the importance of a strong merchant class, you will focus more on naval expansion.

Depending on your position, you can focus on either land technology, naval technology, or a halfway point between both. There are many options at your disposal. Pick whichever ones seem to make sense for your position or style of play. If you want to expand by land, you want to focus on land technology, and make your nation more aristocratic. This will reduce the cost of soldiers and make give them higher morale. If you are a large country, you should consider having the quantity of your soldiers be more important than their quality, especially if your are ahead in technology.

When fighting, try to lure you enemy onto the plains or the desert, where you can crush his army with a large force of calvary. Calvary is ideal as a shock force, especially when commanded by a historical leader. While the horses excel on the deserts and plains, they are horrible on any other type of terrain.

Your economy depends on the value of your provinces, the amount of taxes you get from your people, gold mines, trade, and the most important factor, stability. At the end of each year you collect census taxes, so every January 1you should be looking at a big payoff if you are doing things properly. When determining your domestic policy settings, try to focus on programs that will improve trade efficiency and production efficiency, as well as stability. The more stable you are, the better your economy will perform.

These basic guidelines should give you enough information to play one of the more powerful countries. However, If you want to truly become a master, you will have to learn through experience. The in-game tutorials may help you if you are totally lost and confused. Europa Universalis II is definitely a game that is easy to learn and nearly impossible to master.