So my main gameplay loop with EU5 so far was playing into 1600s, seeing that everyone massively outproduces me and finding out that I was playing with my hands tied behind my back in some major way and restarting the campaign. I went through the loop four times and now I've got to a place I am proud of: kingdom of Eire, 400 gross in 1560s, successful siege of London which can be repeated every truce, a lot of money for colonies in Canada, from this place path to expansion is fairly straightforward. Here is how I did it.

I started as Connacht, but advice here will work for every tribal nation on the island. Most of them get less levies than Connacht, but overall strategy is the same. Before you unpause you should do following things:

Revoke Creaghts priviledge. It makes raise much, much more levies. Considering that almost all your neighbours do not revoke it you get an insane advantage at the start.

Give peasants levy privilege and the right to move around. This makes your population more dynamic. flocking to places where you want to see them

Destroy starting fort (if any). If you have to rely on fort in this stage — you have already lost and 0.4-0.8 ducats it takes is inexcusable this early in the game

Give privileges for centralization. Centralization is an ABSOLUTE must mainly as it increases your crown power

Max out Tribal Cohesion and stability spending

Automate General and Admiral appointments

Then I wait for 4-5 months for everyone around to make alliances and unprovoked attack the biggest one I can beat, usually in the first war I try to take Sligeach, since its a town and thus I will get access to burghers and insanely good privilege for roads, which also gives centralization. My usuall allies are Munster and Thomond with Thomond getting [redacted] by Clanricarde. When starting the first war I send spies to every neighbouring nation fabricating either subjugate high kingship or push back colonisers.

Your goal at this stage is to wage as many wars with independent tribes as you can, because England and Scotland are extremely grabby and you will need all the territory you can get.

At this stage you have to decide where your capital will be. Going for a sea province is a no-brainer, before good roads maritime presence will carry you by increasing control in coastal provinces. For this reasons I make Galway (Gaillimh) my capital since it already has a town and Roscommon, Mayo and Claire as integrated provinces, the rest I give to my vassals.

About halfway I send diplomats to both Scotland and England to improve relations, because you never know which one would be more beneficial later.

Important: take at least one location in the north-east. This will decrease your diplomatic distance to both Scotland and England allowing you to make treaties with them easier.

When I conquer provinces I try to destroy monasteries, temples and bardic schools since they tank your income early game. You can build them later when you get your economy together.

At the end of this stage I usually have 3 vassals and no land that does not belong to me or my vassals or England or Scotland by proxy.

Also approximately here you want to reform to monarchy, which will have numerous benefits, including autocracy government policy which gives a lot of crown power.

Now you stand before first major challenge: The Pale. Even with all provinces conquered you will have less levies than them, but they have pretty weak economy, which makes them go bankrupt a lot of the time.

Also, now you have to decide on your final capital location. Obvious choice is Dublin, since it is really developed, has a lot of pops and has really good potential for growth. the problem is that it is controlled by the Pale. Also Dublin has amazing RGOs, compared to other parts of the island: wheat and honey

There are two strategies to approach this stage of the game.

• Form a defensive league with Scotland and rush early carracks/carracks. England is unable to get a large fleet early and a lot of their fleet will be light ships. At the cost of maritime presence and A LOT of gold you can build fleet of the same size as them, but consisting of heavies and, therefore, much more capable in battle. Use your navy to destroy english transports and you pretty much garanty that they will be unable to interfere into war on an island.
  
• Become a tributary of England and fight Pale 1 on 1. This has an added benefit that you can take Dublin before it is converted to english culture as opposed to anglo-irish, requiring you to spend less capacity to assmiliate it.

Important: becoming a tributary of either England or Scotland is AMAZING. First of all you can revoke tributary status unilaterally once the truce wears off AND for the the duration of it you get protection from the other side AND you can fight other subjects 1 on 1 without overlord interfering. If England or Scotland declares war on you a lot of the time you can just become their tributary immediately, pay some fee and undo it when you see fit.

If you can conquer Dublin early on, I strongly suggest moving your capital there, if not create a new market at your capital. This will massively boost your trade profit and be very beneficial as a whole. Also consider making a vassal out of your old capital if you decide to move it on the other side of the island.

There are a few things you have to consider here

• Lumber in Munster is a must, a lot of lumber gives you much cheaper RGOs in your main territory
  
• There are two provinces that produce stone, both are in Pale and both are developed decently by AI, I have not had stone shortages, just make sure you have enough masonry guilds so you never build at less than 30% reduction cost
  
• Literacy. Restricting your territory also helps you to drive up your average literacy, allowing for faster advancements. You will need this since institutions spread to your backwater much longer
  
• Trade offices. while you can't really ally or get a guarantee from France, you can increase you relationship with them and build trade offices, increasing your trade.
  
• General routine: increase control, increase crown power, build marketplaces to the max, build RGOs around your capital to the max, build up your capital and urbanise overall. There are definitely some strategies like using clay from Mayo to make insanely cheap pottery, or using wheat from Dublin for distilleries, but I did not focus on them so can't really speak to their merit
  
• Fishing villages are amazing. They increase your maritime presence and trade capacity, so max them when you can

After that you are pretty much set for game: defensive league with Scotland just never breaks, maintaining fleet on par with English, I suppose you can try to go to war with Norway to prevent them from grabbing America, but I maintained no army, no forts and focused on economic development since currently there is a bug that prevents laborers from joining levy and this severely restricts your military capability.

Increase your literacy, rush printing press when you can and go to New World. I failed to get there earlier than England, but it is definitely doable, then you will have LOTS of RGOs for cheap fur, lumber, all the raw material good stuff.

Do not bother trying to get alliances before you get to kingdom: you are a backwater island for now and distance penalty hits really hard. Easiest way to form a kingdom is by getting 20-30 prestige and canonizing ruler, after that prestige falls of really hard, so make sure you have enough gold and population to do that, once again, promoting to kingdom gives you extremely good bonuses to almost everything.

I hope this guide was useful, I definitely deepened my understanding of the game mechanics from this playthrough and found out how insanely good this game is.

Thank you for reading.

sometimes vassals of Pale lose rulers and fall into Lordship regency without ruler massively lagging your game. Just use console commands to either kill english king, or annex them as Pale (this option is for added challenge). You can find out if this happened by spammed Lordship Regency notification in your feed.