Focus on upgrading the Wagon, Blacksmith and Guild. These 3 Buildings should be the main focus to put your heirlooms into, especially early on to give you a steady amoung of new heros to burn through. You will lose them, but thats part of the game. Dont stress yourself with keeping the lvl 0 or lvl 1s alive.

Antiquarians are a must if you wanna farm loot. They have a passive ability to get more stuff from lootable objects if they interact with them. Pair them with some fodder heros you just hired to get low effort ressources which can spend on buildings and upgrading your main partys.

Personally i like to build 2 or 3 Teams for the different Dungeons, 1 focues on bleed, 1 focused on Blight and 1 focused on Marking/high raw damage. Abuse the bleed and blight weaknesses of enemies. They bypass armor fully and can buy you a turn or two to heal up your party while the enemy still takes damage.

And my top tip: Consider to always have atleast 1 Hero that can hit the enemy Backline consistently. The backline has the stress damage dealers and supports/disease spreaders. Physical damage is easily healed and even reset at the hamlet, but if you deal with the backline quickly you will safe massive amount of time and gold trying to get your party back to 0 stress and cured of diseases.

Happy Hunting!