Edit; it's cool i'm getting downvoted for this.

Do you even know how arrogant you sound right now?It would be understandable if your tips were somewhat helpful but they're just plain wrong.There's so much wrong in all of this.

I'll start from the top.

Get a grasp on terrain modifiers when attacking and defending. Grasslands incur no penalties for attackers unless there is a river crossing which, in Europe, is the case 75% of the time. Descending in order from most severe is Mountains, swamp, hills (If a leader has a high enough (I do not know how high to be honest) movement modifier he can neglect river crossing penalties).

While there's nothing wrong here,you leave something very crucial out(which alot of player are'nt even aware of).And that is that both Forests and Woods which are both very common too give a -1 modifier to your rolls.That means that even if you don't cross a river you might get a -1 modifier due to Woods which are very common throughout Europe,especially in northern Germany.The same applies to Jungle(often found in the New World),Hills(which too are very frequent throughout germany),Glacial(very rare),Highlands(and no Highlands are not the same as mountains) and lastly Marsh.What you've also forgotten to add is that all of these Terrains also modify Movement cost(the time it actually takes you to move) and the Combat Width.

Also you never even mentioned Combat Width which is a most crucial part of combat.

Forts! Right. I think I recently concluded that it's a good idea to put your forts on Grasslands (terrain type) or other terrain types without penalties. Why is this you ask, well, if you're declared upon you'd usually want the AI to make the first move. Having forts on grasslands basically baits the AI to go somewhere where you can fight them evenly.

This makes absolutely no sense at all.If you want that the enemy attacks you then why do you want him to attack you on the terrain where he does'nt get any negative modifiers from which you'll benefit?You should rather place them on things like mountains and hills and higlands,where not only they'll get bad modifiers from attacking you but also there your forts get defensiveness boni. Also these places have the lowest supply modifier of +4,which'll in turn give them even attrition which is then in turn better for you.

Now the next section is well,the worst offender here...(i don't want to create more of a wall of text so i won't copy it).

First of all i sincerely hope this list of Ideas there is not a ranking because if it is,it is horrid.Just plain horrid.

Second,Espionage?Es fucking spionage?I mean i get that some like it for it's very limited utility and with the new dlc added it got atleast some utility for non european nations but come on!It's one of the worst idea groups in the game.It has very limited utility and severely lacks in impact if you compare it to all other idea groups.It's use is mostly for MP games in which the AI does'nt get any Boni which'll just nullify the effect of Espionage and i would greatly advise against ever taking this horrible idea group.

Whether you'll need the Religious idea group is a question I've often asked myself. If you're a German, French or Eastern European nation it's usually recommended as a second, third or fourth idea group. Taking it as a fourth is a bit late, but doable, since the Protestant reformation and later counter-reformation will happen just around the second and third idea slot (around 1490-1530). This is the time where you need missionary strength and missionaries. If you're expanding in the Middle East or otherwise outside Europe, you'd need religious idea group as well.

Nononononononononononono,there's just so much wrong with this.First of all you really don't need this idea group for it's missionary strenght if you're inside Europe and don't plan on expanding into Africa/Asia(Or to be more precise if you don't plan on expanding into Sunni land). Now don't get me wrong i don't say that getting Religious ideas is bad for european powers but rather that the reasons you've shown to us are just bad.

Your merchants are usually set up in an ideal way.

No they're not.In fact i think most of us here can agree that they're placed horrible.There are ofc some exceptions to that but most of the time they're placed very badly.Also this is bad advice for newcomers as this'll discourage them from looking on the trade map mode at all and they'll most likely completely forget about trade.

I'll always recommend a player to try to colonise.

Don't say always.You would'nt want a Prussia player to encourage on taking exploration as his 2nd idea group.

If you do want to colonise then getting Exploration idea group as a second or third idea group (I usually take it as third) is about right. You don't need it earlier.

You don't need it earlier but if you're let's say,Portugal then the incentive should be to get it asap or else you won't be able to grab the juicy mexican gold provinces.

This is a huge bonus that people often overlook when pitting one nations National Ideas against another.

Mercantilism is not part of the national ideas of a nation.There is no national idea which increases mercantilism.Otherwise it would mean that all german minors would have more mercantilism because Ulm has German National Ideas.It's just that some nations have that set amount of 25% rather than 10%.

Once the reformation has settled you'll notice that Protestant and Catholic nations will ally within each faction. If you want to stay buddy buddies with some of the Great Powers (France and Commonwealth, notably) it can be worth it to stay catholic. But who would want that?

That's not a good reason to stay catholic as you'll most likely still will be able to ally heretics.The minor opinion modifier it gives you does not influence your allies too much.

Forts are a bit bugged as of now (AI walking past you defenses) just so you won't be confused about the mechanics. They worked splendid previously. One of the best additions to the game since release in my opinion

No they're not.

Well that's all for now.And i really hope this was'nt a ranking of your ideas because that would mean so much more writing...