I dunno if AI can tell you but I can.
1. Optimize the income
- turn as much territories into states as possible. Your income will go up insanely
- build as much buildings as you can
- convert and accept as much cultures as possible
- convert the religion of all provinces
- send frigates on the most lucrative trade protection missions
- send traders to the most lucrative markets, in combination with the frigates, if possible
2. Alliances
Make proper alliance. Osman Empire is not a good ally for example. They will use you to help them taking European countries, then declare you a rival. In some cases it is good to make alliances with rivaling countries, in others it is not a good idea. For example it is good to be allied with Sweden and Russia. They are enemies, but their alliance with you will prevent them from going to war with each other so you can keep them both. Alliances are important even though they can drag you in countless wars.
3. Military
- Maintain a large army. If your army and fleet are too small, it is hard to get strong allies and you will be attacked.
- Always drill your troops, even though it will take time to make them combat ready then. The drill makes the troops stronger and you will see that the generals you hire will become better in the course of centuries. If you stop this and have no wars, the skill level of new generals will decrease again.
- Besieging fortresses can take a long time. Take them step by step and deploy troops nearby too. If the armies are too large, they will lose troops so make smart decisions and rather have more armies in nearby provinces than a huge army besieging a fortress. Of course you need to watch them closely so that you can send them quickly.
4. Ideas
Military ideas are the most important. It is a good idea to get economic and diplomatic ideas at first but in the end you will have enough money anyway and only the military bonuses will count. Whatever groups of ideas you like, first look up what additional bonuses a group can grant in combination with another group.
5. Difficulty
The difficulty depends on various factors. The country you choose for example. The Osman Empire is very strong, so choosing them makes the game easier. Spain is also a good choice but I prefer custom nations with custom bonuses. I mostly play as republic with Jewish religion.
Pick a strong country and play on very easy for some rounds. What I wrote here is just a tiny fraction of what you can learn by playing. One of the game tips says you can learn new stuff even after 1000 hours of playing!
