One Life
Avoid death, be smart and you'll get this
[Missable]

The One Life Achievement needs to be completed on your first playthrough, if you die during your first playthrough you'll need to delete some registry files or try again on a different pc.

Press the Windows key + R and type regedit in the search box then delete the folder below.
Computer\HKEY_CURRENT_USER\Software\GexagonVR\Nevrosa: Prelude

Cyclops
Use a pen to blind the monster
[Choice Dependent]

Stay Tuned
Scare the monster with the right radio tune
[Choice Dependent]

Just after taking the key from the spider you'll turn around and zipline onto a table, once you land on the table a monster will emerge and you'll be attacked.

Now you can choose to stop the attack and complete the scene by correctly tuning the radio
for [Stay Tuned] or by stabbing the monster in the eye with the pen for [Cyclops].

it is recommended to stab the monster in the eye when attempting the One Life achievement.
You can also stab the monsters hand with the pen when he swings at you to block the attack.

Spider and the fly
Provoke the misty spider to attack you
[Missable] [Buggy]

This achievement might take a few attempts. First take the key from the spider and turn around as if you were going leave but instead turn back around and start hitting the spider with the key.

Sometimes this will just fail to unlock or the key gets knocked out of your hand and out of reach.
Provoking the spider will cause you to die and restart so save this until after unlocking One Life.