General Techniques to protect oneself
In the world of the afterlife, astral or if you prefer, just as there are dangers in the material world or physical reality, therefore, a good researcher must be able to protect themselves, not putting off this task to third persons or entities guardian, the you have such a task support to your own secure, but can do little or nothing if the latter, crossing thresholds of situations that can not handle, and then be prepared.
At the bottom of this writing there are suitable links to answer your questions, or "curiosity" regarding the topic.
In the meantime, I invite you to read as many books as you can find on the astral world, its inhabitants and the dangers they might encounter, since the subject is vast and you can not place it in a website with sufficient completeness.