Every action you take costs your body something. Thirst and hunger build up in the background, the cold creeps in, and a tired hero rests badly. None of it is urgent on your first turn, but all of it catches up. Plan your first nights around four things: water, fire, food, and a safe place to sleep.
Know what is draining you
For most heroes, thirst rises by 1 every 2 actions and hunger by 1 every 3 actions. Both run from 0 to 100. Once either one is full, you lose 2 Health each time it would rise again, until you drink or eat.
Thirst fills first, after roughly 200 actions. Some afflictions and divine wrath make both rise faster, so check the bars now and then rather than waiting for the warning.
Find water, then make it safe
Carry an Empty Bottle. Rooms with water offer an action to fill it. A Well, an Underground River, a Kitchen, or a Garden gives a clean Water Bottle, which removes 30 thirst.
Most other sources, such as bogs, streams, lakes, seepage, dripping pipes, and melted ice, give a Dirty Water Bottle. It only removes 10 thirst and costs 4 Health. Drink it only when you have no other choice.
To make dirty water safe, use the Boil water option at a Burning Campfire, or filter it through Charcoal with Rags. Either way it becomes a clean Water Bottle.
Light a fire
An unlit Campfire can be lit with a Stick (used up), a Flint Stone, candles, a Burning Torch, a Fiery Ring, or the Spark and Invoke Fire spells or scrolls. You can also build a Campfire yourself, for example from a Stone and a Wood Piece.
A Burning Campfire beside you warms you whenever you are colder than normal, adds 20 Comfort, and lets you boil water and cook. Stomp it out before you leave if you would rather not leave a trail.
A fire in an ordinary dungeon room fills it with smoke. While you stand in smoke, every action costs Stamina, and thick smoke costs more. When your Stamina runs out you start to suffocate and lose Health instead. Build your fire where the smoke can escape: an Underground Forest, an Underground Cavern, a cave, or anywhere on the surface.
Eat cooked food
Raw meat fills you a little but costs Health. Cook Raw Meat at a Burning Campfire to get Cooked Meat, which removes 35 hunger and restores 5 Health. Raw game meat roasts into Roasted Game Meat, which removes 65 hunger and restores 15 Health.
With a fire in the room, raw meat or fish can be turned into Food Rations with a mushroom, an Apple, Berries, a Large Egg, or Wildroot. Rations remove 50 hunger and travel well. Unknown mushrooms are a gamble until you have tasted each variety.
Stay warm
A bare room slowly chills you unless your clothing and armour insulate you. Standing in flood water chills you further. On the surface, nights are colder than days, and the hours around midnight are the coldest. Underground rooms are sheltered from the weather and the time of day.
A Burning Campfire in the room gives the most warmth. A lit torch gives less warmth while you hold it, and a little when it lies on the floor of the room. Put a torch away and it goes out. To light it again, choose Light in your pack with a fire in the room, another burning torch, a Flint Stone, or fire magic. A drink of Wine, Mead, or a Bottle of alcohol, or a Potion of Warmth, brings you straight back to a comfortable warmth when you are cold. When you are too hot, any drink cools you down. If your temperature bottoms out, you lose 1 Health every turn until you warm up.
Choose your battles
A room with an enemy in it is not a fight you have to take. Enemies that have not noticed you do not attack or follow you. They only chase you once they are angered.
If a room holds something you would rather not fight, move on before it engages you. Sneaking helps you pass unnoticed. Save your Health and Stamina for the fights you choose, and do not rest until the room around you is clear.
Sleep somewhere safe
Stay spends one turn resting in place and recovers Stamina. Sleep keeps resting turn after turn, for up to 30 turns, until you are fully recovered or something wakes you.
You cannot sleep with an enemy in the room, in a collapsed, infested, or gale-swept room, or when your Comfort is below -50. You wake early if hunger or thirst passes 90, or if you become dangerously hot or cold.
Sleep does not wake you for bleeding or poison. The game warns you before you sleep with an affliction that costs Health each turn; treat it first. A fire, Fur Bedding, or a bed raise your Comfort and make the room a better place to rest.
Your first night, step by step
Keep a bottle and a Stick or Flint Stone in your pack. When your thirst and hunger pass about half, look for an open space with no enemies, such as an Underground Forest or a cavern. Light a fire, boil your water, cook what you are carrying, and eat. Then sleep beside the fire, and leave with full bottles in the morning.