Tips
General roguelike skills
Experience playing other roguelikes will go a long way and the following skills will help you whether it's Golden Krone Hotel or any other roguelike.
Play slowly
Traditional roguelikes are turn based. The natural instinct when in a desperate situation is to start playing faster, but playing slowly is the proper response. Patience is the name of the game.
If you realize that you're a turn or two away from death, try taking your hands off the keyboard, getting out of your chair, and maybe grabbing a cup of coffee or tea. Come back with a cool head and spent at least 20 seconds contemplating your next move.
Pay attention to what's on screen
This goes back to the previous point. Many players ignore their low health, hunger, low mana, status effects, and on screen opponents until it's too late. It is taxing to pay perfect attention to these things all the time and you can ignore them when everything is going well. But as soon as you see more than one monster nearby or a monster you don't recognize or you have less than 50% health, you should really stop and take inventory.
Use all your tools
Roguelikes put you in bad situations, but they also give you a bunch of powerful tools to help get you out. In Golden Krone Hotel, you have: a revolver, potions, spells, vampire abilities, and environmental hazards. Only using your bump attack is like fighting with your hands tied behind your back.
Back down
Other genres have conditioned us see games as a linear sequence of unavoidable obstacles: keep trying to beat the level until you succeed. And they've treated us as powerful heroes capable of overcoming any challenge. Neither of these are true in roguelikes. The dungeon is much more dangerous than you are. If you refuse to ever back down from a fight, you won't get very far.
In GKH and many other roguelikes, you are intended to encounter situations/monsters/branches that you are too weak to deal with. It's OK to run and come back when you're more powerful. It's OK to take a different route. It's OK to not kill everything.
Something that new players do all the time: walk onto a new floor, see 5 monsters they absolutely cannot handle, and without any sort of buffing immediately run deeper onto the floor (and away from their only escape).
Exploit
One particular weirdness about roguelikes is how they handle stairs. Monsters can only follow you up stairs if they're directly adjacent to you when you go up or down. What this means: if you can put even a single tile between you and a monster, you've made a 100% clean break and can escape to safety.
Some players use "stair dancing" to fight enemies one at a time, but at the very least you should exploit stairs to make escapes.
Fight in favorable positions
Generally this means fighting multiple enemies in hallways instead of open spaces, so you only take damage from one at a time.
But there are many other considerations in GKH depending on your form: fighting in or out of darkness, near or away from sunlight, and out of water.
Human vs Vampire vs Werewolf
-dodging magic, hallways are the worst
All About Lighting
-the day night cycle -vision -can kill vampires -moonlight can turn humans into werewolves -sunlight can buff and heal greenmen -can be produced or used by the FOCUS spell -many spells (FIRESTORM, SHOCK) and firestorm produce light for one turn