In Buddhism, one big one would be not keeping in mind the primary goal of non-attachment. Non-attachment to bliss, horror, expectations, and certainly not to any goal.

The Biography of Naropa would make an amazing horror movie. Really wild read as well.

Meditating alone for starter? Meditating too long. Meditating before your day start and you get into stressfull situation.

It should be done step by step, carefully.

I think philosophers talked about habitus, and nowadays we might be able to "fix" phobia with a mix of MRI and reinforcement learning, slowly. Or how to reduce your fear of falling when rockclimbing, by falling "on purpose" when you are in between pitons by an increasingly large length.

Meditating without an experienced and well trained teacher.

It's worth ruminating on the fact that all medicines are also poisons. This is why homeopathy is so safe.

Ah, this needs explaining - any tool which can cure can also cause injury. Too much of a medicine will kill.

Homeopathy is useless, which is why you can't harm anyone with it.

Meditation does work, which is why it can also be dangerous.

Check out Kundalini Yoga.