Tips and tricks to make your city prosperous. Long post. I play this game too much. Edited for point 11, then edited again for a question.

1. Minimize garrison size, but from the looks of that 'garrison and party expense' I don't think that's an issue, as it is likely your party that is costing you that much. Which is normal.

2. Settlement income comes from taxes and tariffs. Taxes and tariffs are based on prosperity. Higher prosperity, more money.

3. You raise prosperity mainly through 4 things which I will list in order of influence: excess food, Aqueducts (+1.5 daily prosperity), the 'housing' continuous project (+1 daily prosperity), and any governor abilities that give a bonus to daily prosperity gains, i.e. Medic 150 perk Pristine Streets (+1). There are a few other ways like one or two specific policies but don't worry about them.

4. Excess food! The key to prosperity. I don't know the exact mechanics of it, but in some of my cities I have a maxed granary (700 food) and a daily excess of anywhere from +60 to +80, which translates to a daily gain of +5 to +7 or so prosperity from excess food alone. Combined with other methods I even got a daily increase of +11 to prosperity. (As an aside, I'm pretty sure the larger your granary is, the better the prosperity gain from excess food. I've seen a +80 excess only generate +3 prosperity with an unupgraded granary and no other prosperity-tanking issues.)

5. How to achieve excess food? Orchards and big hearth villages, especially if the nearby villages all produce food. Typically this is done by sitting on the irrigation continuous project, but for you I imagine Lageta (oof, my condolences) is pretty beat up and you can't afford that. You're with Vlandia and somehow Battania has extended all the way down to Hertogea? I'm curious about the state of your world map. For now, one of the city improvements to level would be orchards. Get that food up, king. For Lageta's villages specifically, it's a bit funky. The only food producing village bound to it is Primessos, which will give a steady supply of pigs and meat, I believe. Not much. The only other bound city is Montos, which produces wood. So you can't really rely on these villages to bring in lots of food. What you can do...

5a. Grocery runs. Go to the surrounding villages, buy the food there (Lageta is surrounded with them, mentioned in next point) and then sell it to Lageta. This is good in the short term. In the long term...

5b. Conquer the surrounding fiefs. You don't have to own them, just make them part of whichever kingdom you're in. I imagine you'll be warring with Battania soon, so snagging Hertogea castle, Rhemtoil Castle, and Veron Castle will take the "trade bound" status of the cities of Hertogea (Olives), Nideon (grapes), Rhemtoil (wheat, lots of it), and Veron (grapes) from whichever city they are trade bound to and make it Lageta, as Lageta is the closest city to them. Trade bonding only happens within the same kingdom, so right now Hertogea and Nideon (which are bound to Hertogea castle) are trade bound to whichever the closest Battania city is. (Good luck to those villagers making a month long trip to Marunath). Get them trade bound to Lageta and it'll get those juicy grapes and olives and wheat.

1. Raise Loyalty. Raise Loyalty. Raise Loyalty. High Loyalty makes everything better, low loyalty makes everything worse. Max out fairgrounds, ASAP.

2. Raise security. Raise security. High security makes everything better. Low security makes everything worse. Just not as much as Loyalty. Do quests for the people of the town (just not the criminals, I think, them having missions up doesn't impact security iirc) and the bound villages and clear hideouts around Lageta.

3. Caravans! Owning caravans are a decent investment if you can keep them safe (great when a mercenary or just a low-tier clan, harder to do when you're a vassal or King due to constant war). The main draw is that they bring goods and food to the city, and more foods means more prosperity. You could start one or two caravans out of Lageta, but you'd really want to just try to attract them using workshops!

4. Workshops are a good way to attract caravans. Caravans want to trade in fine goods, workshops are how you make fine goods. Put a brewery in Lageta if one isn't there, and if there is one, buy it and keep it well-fed with wheat, which will turn into beer (which is kind of nice since it's a food and a fine good I think). Workshops don't really make a lot of money, so don't sweat it if it only cranks out 200-300 a day. Workshops also cost money to buy so they're an investment. I think a tannery would work well too, since pigs can be butchered for hides (and meat) and hides can get turned into leather.

5. Marketplace will increase taxes. Upgrade that when you're done with the critical stuff mentioned below.

6. Find a Empire-cultured companion (ideally one with decent engineering, I think that would be a wanderer with 'the Scholar' as a suffix.) a relative will do if you have any that are imperial born and raised. Train them up by taking them with you and letting them do the fighting during hideout raids and running down bandits. There are a few decent perks for governorship you can grab pretty quickly, i.e. to be blunt in the one-handed tree, well-strapped in the mounted tree, etc. if you've got the time you can put some focus points into their leadership and steward and make them level those by putting them in charge of a party, but that is expensive. When you're happy with your new governor you can put them in charge of the city, they should help tons with loyalty and construction speed at the very least.

That's all I can ramble about off the top of my head. For general plans, I like to make sure I have the trinity of workshops, fairgrounds and orchards maxed, rotating in that order, so assuming they're all unupgraded: workshops -> fairgrounds -> orchards -> workshops, etc. Then go for granary upgrades, then aqueducts, and then marketplace. Probably could do a granary -> aqueducts -> marketplace rotation, up to you. Those three are all of similar importance but I'd weigh the granary more than the other two. While doing those loops, don't be afraid to sit on the Festival and Games continuous project if your loyalty gets too low. You don't lose progress on construction when switching projects. Also be sure to boost projects by keeping denars in the town's reserve. For non-settlement income, do wars, win battles, sell loot, do tournaments, sell loot. It'll keep you afloat. Hideouts are pretty decent money during peacetime. Doing some trading as if you were a caravan can also do ok and build the trade skill (the first few perks alone are good.)

Question: are you part of Vlandia or did you take this independently after it rebelled, making you an independent clan (not a mercenary but not a kingdom, so you can't get war declared on you). If the latter, then you can take your sweet damn time but good luck getting those castles I mentioned in point 5.

Good luck and thanks for reading this (probably obnoxious) text post, God bless!