So, here is a little guide for the people struggling with the game:
I'll start with the most non intuitive mechanic of the game, the crafting and selling:
Do not depend on dispatch requests to get money. They are finite and won't be enough at all for your needs. They can still help you to kickstart your shop in the early days (there are some juicy ones that will give you a lot for that part of the game), but their main use is to unlock new ingredients.
The delivery requests are not worth it, they are slow, offer little money, and require you to look for or craft specific items.
To increase your pool of dispatch requests, you need to invest in organizations. The higher their level, the more quests they can give you, but you can only complete each quest once. Increasing the rank of an organization also allow them to sell the ingredients you unlocked.
With all these ingredients, you need the recipes to do something with them. You can get the recipes by investing in cooking/blacksmithing/mixing.
Now you can go to the production screen and make new products. The rank of the recipe does not matter at all (though higer rank tend to require more ingredients, which is good), only the price of the ingredients do. So to increase the price, sell items that need many ingredients and choose the highest rank available. Then change the price to five time the ingredients price.
The game tell you that customers have a budget, and a few of them won't buy from you, but the increase in income is still totally worth it. Their budget also increase as the game advance, so don't worry too much.
Prohibited items, items that use illegal ingredients, and addictive drugs sell well even at higher price.
Once you have some recipes with higher level ingredients, the money stop being a problem and you can buy all the upgrades as soon as you unlock them. Oh, and you should try to increase visitors as much as possible with events, since without customers, you can't sell anything. So keep the store clean to increase the visits and secure to prevent thugs to chase your clients. You may think that the bounty make farming the thugs interesting, but by the time you have chased them, they'll have chased most of your customers, and the loss of sales is definitively more than the bounty you gain. Good receptionists also improve dramatically the price.
For the requests themselves, forget about the ranks, what matter are the stats. The rank does not seem to change the chances of completion as much as it should, beside the fact that higher ranks have better stats. I managed to complete a 8 stars quest with only E-F ranks that had all the right stats for it.
There are two types of stats that affect requests, skills and traits.
The skills on the left represent the capabilities required for the completion. When you start a quest, the skills that affect the quest will be in pink. When you select a character, if they are in light blue, it's either negative or too low to complete. If they are in pink, it could be better but you still have some chances of completion. If they are in yellow, you have enough and a high chance of completion. Remember that all the skills need to be high enough, two yellow and a blue have a lower chances of completion (it can still be done though).
The traits on the right represent the chances for the party to have bad outcome even if they have all the required skills. My speculation on what they do is that loyal represent the chances for the adventurers to go in another guild, ethic the chances for him to run with the money, action the chances for him to be too lazy to finish the request and libido the chances to get a positive/negative trait (not sure for this one, and it only appear in sexual requests). I have never seen look and sales, so I'm not sure why they are on this screen.
All these skills/traits are cumulative for the whole party, so even if you have an adventurer that have the skills to make the request by himself but terrible traits, you can balance it with characters with good traits of any rank. And even if he has good traits too, fill all the slots with adventurers you want to level up, because if there is not the required amount of adventurer too, it is likely to fail.
The reward is what attract adventurers, so to attract higher ranks ones, you need to increase it.
Increasing the power of an organization also increase the overall rank of its adventurers.
For the medals, your best way of collecting them is the dungeons.
When the story require you to clear a dungeon, don't rush it, kill the mobs on every floors and gather the resources, it increase the number of medals you get at the end. Since you will return at 17h anyway, no matter the hour you stop at, you may as well farm the medals while you are a it. Just be careful to not miss your objective, but unless you failed an event and lost time, you should be able to do it easily. The events are also a good source of medals.
Also, don't bother upgrading your non unique characters, it's more efficient to replace them with better ones, since the money is easier to get than the medals, so keep you eyes open for new applicants. Your unique characters cost 65k to upgrade to rank S, so it's better to keep the medals for that.
You may also be tempted to spend all you gains in the prostitute dream in medals, but it's a trap. When you buy something, it gain a level in price, which more than double it. Every item lose a level in price the next time you come in the dream. So if you purchased ten time something, the price will be as if you purchased it nine times the next time, so it will take nine other visits for the item to be at its base price again. The most efficient way is to buy a little of each per visits. The point are also better spent for elements, which seems harder to find outside, the only other source being the dungeon which always give elements lower level than the best gear you unlocked. And you will never have enough high level elements in the dungeon to craft what you want.
Once you have maxed all the elements, spend all your earning from the dream on silver medals. Don't bother with copper (beside buying it once each time for cheap), you will have maxed you characters to rank S way before you have maxed their skills to rank 8. The cap to the price on silver medals is 6.6m and on copper 3.3m. So if you can't buy several time the silver medals at max price at each visit, don't bother buy it more than once and keep the price low until you can.
For the dream prostitution, the higher level the play, the better the reward. Non unique characters give lower rewards, since they have much worse stats, so prioritize unique characters for high ranks customers. When you have enough unique girls, just don't bother with the non uniques (they are not very interesting anyway).
All your unique girls should have the sexual skill, it increase their prostitute rank and thus greatly increase your income in the dream.
There are mentions to venereal diseases and impregnation chances, but I have yet to see it happen, the pregnant girls already where before arriving and I have only seen males with venereal diseases.
Not much to say about the combats, they are very easy. Just craft armors for your more squishy characters, spend your points every 2-3 new unlocked dungeons and you'll be fine.
Even with all the girls with sexual skills (which does not help in combat), the dungeons should be a breeze.
Just be sure to have the detect enemy and detect trap buffs.
Somehow, Lucerula is a better healer than Marisel.
As you get more characters, getting a specific one become very annoying, so try to not rely on a single one too much.
For the buildings, don't hesitate to make more rooms than you need, you can destroy them later since money is not a problem. Don't bother with the maintenance price, at the time you unlock the rooms that have more of it, you should be swimming in money.
The large shops are really good and should replace the small ones when you get them. The erotic shop has dubious value due to the lower price of the items it can sell, but I guess it's good for the roleplaying aspect? When you unlock the casino, replace your shops with it.
You only need one resting place for the staff, so use the bath for the women, to also get medals from the customers, but only if you have the space. The men do not seem to bath much (not sure if its a bug, but it's always desert), so only use a staff room for them. Even in endgame, you income will be much greater with rest rooms, but their level does not seem to matter much, so when you need space temporarily (to unlock plays with girl), just destroy them and remake them later when you have space again.
Only the basic playroom is necessary, since you can unlock all the locked plays in it with a girl once she does it with a customer in the dream. But it take quite long to get it randomly from customers, so you should buy the luxury room and cosplay room just for unlocking them with your girls, then destroy them because once unlocked, you can just play the scenes at the playroom.
For the management of your workers, I prefer to keep the reception and production to the minimum to make sure the right characters use them, so I don't put anyone on copy because they tend to steal their jobs or go to the wrong one. Unless you get someone with A rank in reception and a craft.
Only two crafters can work at the same time, so you need three of them for each craft to maintain a stable production.
A good amount of cleaner and security prevent pollution and crime to increase, and you need as many people on purchase as you can if you want to make money by selling, since without supply, you can't sell anything.
I'm not sure how the workers choose which production job they will do, but it seem random, I often have my blacksmiths peeling potatoes in the kitchen and my cooks hitting the anvil. Since they can't make anything above their rank, it's pretty annoying, but not gamebreaking since money is easy to get. It just seem inefficient. Or maybe only the rank matter, not in what. Maybe a legendary blacksmith can forge legendary ice creams when in the kitchen...
High rank purchase and security seem to be the easiest to get, the rest seem rarer. Cleaning seem to be the less reliant on skill, so I tend to dump the less useful clerks there (looking at marisel...).
Others random tips/comments:
-Alt+enter for fullscreen
-F8 to accelerate the game
-F7 to slow down
-If you get a game over no matter what, it's normal, that's part of the story, you carry over almost everything in the next loop.
-Don't bother hiring only males adventurer on requests to prevent the females from leveling and avoid high level rivals prostitutes, it does not work. I tried.
-It's probably a bug, but you can put inexperienced girls in mastery and bewitching in the prostitution dream. To do that, you only have to exchange her with a girl already in the category, but you have to do it by selecting the other girl first.
-Accumulating money during loop 3 is useless, you will lose it all at the end of it (around day 85 for me), so spend without looking twice.
-Don't be afraid to use gold medals, their max reserve is low but you get them back fast.
-There seem to be a bug in the result screen at the end of the day. Mixing sales and cooking costs are never counted, no matter how many you sell. Even thought mixing is by far the most profitable.
-When you take the virginity of a girl, you miss the rest of the day, try to do it near the end.
-To upgrade certain part of your shop, you need to upgrade the skill of certain girls (Like Anju for blacksmithing). What skill level on which character you need is written on the right of the description when you place you mouse on it. Don't worry if you don't have the girl yet, it just mean that you are not yet supposed to level it up.
-You can"t miss scenes, you unlock the bad end scenes in the dream even if you never trigger them.
-Some musics are quite nice, I'm particularly fond of callisto's theme and the music of the underground library. it's much easier to farm medals with a good music =)