It might feel hard in the beginning, but once you get one good combo you can just turn your brain off.
Alchemist + Shotgun + brain parasite + parasite choker + gothic corset + enema plug + posture training = ~90 damage crits to half the enemies.
In general though, you just need to follow normal team building practices: need a good healer (clerics are the best, but you can make it work with maids/cows and some niche stuff), a tank (prisoners, warriors, ponies), a DPS (alchemists, mages, paladins, nobles), and a token remover/secondary support (maids are OP, rangers, rogues).
Most classes can do two of these jobs at once and there is usually a dedicated set of items for that (like dance-outfit prisoners are good supports while still being pretty tanky)
wait the pony, maid, puppy, and class like that are usefull ?
I avoidedd all the stuff like choker, parasite, etc...
After a edit of saves (to give me enough money to be able to buy average recruits) and boost Tomo and Aura, yes, it became more easier.
The major problem I met was when my cleric was cursed as hell.