As someone who's played countless Boii campaigns I figured anyone having trouble playing as the Boii, or who would like to see how to build an empire/stable nation with them might find this useful.
The Boii occupy a unique position when compared to the other Celtic factions. They start off with 2 territories at first(1 protectorate, 1 confederation) and are surrounded on each side by a potential enemy. Someone looking to turtle might not want to choose the Boii, as Central Europe is a hotbed for faction expansion--or it traditionally should be. The factions that the boii will most likely have to deal with are their gaul neighbours to the west, the germanic tribes to the north, Rome and the Getai to the south. Sometimes you can expect to fight the Sauromatae or the KB/other hellenistic powers as well, depending on their expansion or yours. The factions you must destroy to win in a long campaign are the swebozes, Areurnoi, Aedui and Roma herself.
The First turn:
As always with EB you have 2 options: unite your forces from across the land and use the army you cant pay for to conquer yourself back into the good graces of a healthy economy, or disband your army and slowly build your nation. As the Boii start with 2 territories they will have a head-start if you choose the slow nation building route. There is one slight problem though...Like your Suebic and Lugian neighbours to the north who are rather plagued by rebel AI desolation, you too have a total of 4 roaming armies laying waste to your borders, raiding as they please on the fringes of your territory. Disbanding might even leave you defenseless against the aggressive rebel AI which has been known to steal a few of my cities in the early game, even when you don't disband one of your less defended cities could be besieged and occupied. For myself, I never disband, I take the risk to grow my empire, and then let myself grow and recuperate my economy. The 4 rebel armies are in the locales of: Tarodunon, Kambodunon, Noreia, and Gorsissa. All of these are your Celtic neighbours, but none of them are so great as the Boii!
As the stratagem for early game slower nation building is fairly obvious (disband + simply let yourself grow to a point where you can healthily but slowly expand), this guide will only discuss the variations of early game conquest, as this is when conquest is the trickiest--you cannot afford to waste your valuable troops!
Stop the raiding, subdue your Celtic cousins:
For myself, since QS added roaming armies to the neighbouring provinces to the south and west, I find myself attacking the roaming stacks and then besieging the cities of their kin. Starting first with Gorsissa, or Noreia, then fighting the roaming armies of kambodunon and tarodunon(provided you have the military strength at that point). If I have enough troops left over I'll besiege kambodunon, tarodunon or asanka. Alternatively, you could first capture Asanka, make an alliance with the lugians to prevent them attacking you--or attacking them if you so desire(but I recommend you leave them be for now, no need to blitz every faction to death) and then capture Lugidunon. It should be noted that these areas dont have roaming armies and can be captured with more ease than the more celticized south, but this wont rid you of the huge devastation economy penalty those southern and western celt armies will give you. You could also attack Tarodunon, then kambodunon, then noreia, then gorsissa if you feel more inclined to strike out westward--just try to keep your conquests in a straight chain if you can, because each turn will plunge you further into debt. Avoid backtracking where you can. The reason why I personally attack gorsissa and noreia first is because of the fact that kambodunon has a strong garrison--stronger than gorsissa, tarodunon and noreia. I also prefer to invade noreia from the west so that I can reach tarodunon and kambodunon/their roaming armies immediately after pacifying noreia, keeping my conquests in a chain as often as I can starting off.
Asanka:
It should be noted that Asanka is the weakest neighbor you have, so total beginners might want to try their hand at conquering that first, then either lugidunon or gorsissa from there. Asanka is also an extremely important border region to control or protect against westward attacks from the east. Asanka is very easy to reach when you attack from the west, but in the east it is mountainous, forested at times and there is a river that also provides a fine natural boundary. Asanka has often been my eastern boundary against the steppe based powers many a time, and I've rarely had to expect much danger of attack from there. Asanka is also ~50% western tribal states culture, so its an easy province to control for you, and a boundary between forest tribalism and western tribal state culture. Asanka is also very important to control because of how close it is to Streuinta--anyone controlling it will have easy access to your original capital and first confederation, the Boii heartlands themselves. Control of Asanka provides the Boii with a fine buffer zone for your capital--but the cost of capturing it or lugidunon will put your borders next to the Lugians, whom you will probably need to fight, ward off or ally yourself with. Asanka's lack of economic and military producing potential is more than easily mitigated by it's strategic importance, and besides that, in the early game each province will reduce your debt by that much more. Asanka is also reasonably sized, such that it is not a nightmare to patrol(eg. Lugouwa: that province is huge, densely forested and has rivers running through it, what a nightmare to patrol), and at the same time it's long enough to allow you a decent route for expansions eastward to klepidava(if you want to conquer that multicultural nightmare of a town). For slower build players looking for less action, Asanka is an ideal target once you're economically strong enough to rebuild an army; it will add to your economy, consolidate your position and also control of it wont make you unstoppable. It's modest benefits, yet strategic values make it the perfect target for a slower build player. Asanka is also an ideal first target for the Lugian players too
Kill the Lugians:
Though I don't recommend this route because it involves so much blitzing, it's more than a surefire way to grant you great power--the lugian regionals are excellent in my opinion, especially their medium cavalry, the Aswinai(sp?). Control over traditional lugian areas will provide you with fine auxillaries for any campaign in Europe imo. The only problems involved are the fact that you'll possibly have to fight the lugian horde after you capture kalisia. You can always try murdering their FMs in battle if you dont want them to horde as well, or other exploits. This is for power hungry players only however, in all my playthroughs now, I try to avoid factional wars early on, instead choosing to grow my empire first quickly, and then slowly picking upon the independents. You can always take lugidunon before the lugians, if you're desperate for a bit of lugian love in your army. Control of kalisia, lugidunon and Asanka should help your economy significantly, however--you'll then be controlling 3 amber route provinces with streuinta, lugidunon and kalisia under your control
The good graces of gold:
So you've did it! you've beaten all those raiding celts, or conquered the lugians, or whatever military strategy to fix your economy you decided to pull. Now you've just got to wait till you climb out of debt to actually build any governments whatsoever! If you're like me and you've conquered your celtic neighbours south first, you could be building any sort of government from allied to confederation--it's really all up to you how you want to build your faction. I do advise you to think about the long term though. You may want migration governments in the less chaotic provinces you own, to provide good recruitment options without dropping your leaders authority points; the building of protectorates is important too, as a cheap form of law providing factional government. It should be noted how good of a capital noreia makes once you stretch even further north, west, east and south--it occupies a very central position in Europe.
For myself, after capturing lugidunon, asanka, gorsissa, noreia, tarodunon, and maybe a segestika and/or kambodunon I figure its time to sit back and relax, let the surplus run in and start building all those infrastructure buildings. There's no need to make war on anyone, by this point you should be strong enough to resist any of your neighbors, and besides if you develop your towns more you'll get cool things like paved roads to speed on your invasions. I do find it hard to stay completely inactive, but I do leave large buffer zone provinces alone such as: singidunon, sarmiszegethusa, patavium and any of the villages close to the other continental celts. I do usually try to take ubioidunon after a time and make that a confederation, as a military bulwark against the swebozes to the north, who can often be quite aggressive. It's important, imo, for the boii to be larger than many of her neighbors, because she is so vulnerable to being attacked by a variety of fearsome powers. Thankfully the Boii have a ferocious reputations themselves :3
My next post will probably be about making a Boii empire.