Timer
When Arnice is hunting or traversing the locations outside the hotel, there will be a time limit. When the time limit expires, she will be forced to return to the hotel lobby. Returning to the lobby manually or when the timer expires will not forfeit any Libra, Blood, or items you have acquired so far.
If you re-enter the battle, the timer will be restored. However, it is recommended to use Doors (checkpoint portals) to cut your travel time and allow you to explore more areas of the location you're visiting. Additionally, you can increase the time limit by acquiring the "Time Boost" skill.
Barriers
When entering areas, the pathways may get blocked by thorns. You'll have to defeat all enemies in the immediate area to remove these temporary barriers.
Furthermore, there are sealed entrances with blue sigils. These lead to new key locations and will only be unlocked as you progress in the story.
Rare Enemies
Sometimes, you'll encounter an enemy with a visible, malevolent aura. These are rare, more powerful enemies that can drop more Blood when defeated. Hunt them down whenever you encounter them to get more Blood.
Traveling
You'll only get to explore the city on foot at night time. From the hotel, you can select the unlocked locations in town. There are locations that will be unlocked only as you progress in the story. Also, if the location has a Door (gate) activated, you can select that sub-area and start from there instead.
Doors
Doors or gates are shortcurt portals that will take you straight to the Hotel's lobby when used the first time around. It's recommended to use them once you find one since they'll serve as your checkpoint so that you can immediately start in the door's location instead of navigating from the location's entrance. Doors are very convenient especially when you're farming enemies for their fetishes or bosses for their Blood.
Destructible Objects
There are destructible objects that may harbor some treasure chests behind them or may contain items themselves. There are two types of destructible objects: those that only your Servans can destroy or those that can be destroyed by Arnice. You'll know if the barricade can only be touched by your servans since they will automatically attack these obstacles.
Chests and Item Drops
Some chests in the game are already displayed in plain sight. You just need to attack the chests to open them and get their loot. Some chests will only appear after you defeat a group of enemies. While most chests only carry one type of loot at a time, there will be chests that can release multiple items. There are also destructible objects and blades of grass that Arnice can destroy and release common consumables/ items.
Enemies drop items as well upon defeat. They usually drop Libra, accessories and on rare occasions, they'll drop fetishes meant for their class. These dropped items and power-ups will disappear over time. However, chests that are spawned by defeating a group of enemies will not disappear so you can always come back for them in case you don't need to loot the contents yet.