It's not terribly difficult once you get the hang of projection, though it can take some people years to get the hang of it (as I did). I would suggest tuning into sensing your subtle surroundings before trying to do anything along the lines of "separation". The reason I quoted that word was because not all of it is separation; some people view projection as shifting the consciousness rather than separating an aspect of the spirit from the body.
I would also like to note that astral projection is not the same as etheric projection, as AP is often mistaken for. EP is when you project to a different space in the physical or etheric plane while astral energy is more cosmic and not as tied to the physical. Etheric energy in this sense is more dense of a non-physical energy than astral energy is, and thus harder for people to work with if they are not familiar with it.
As with any practice, it will likely be easier for you to project if you are in an altered state of conscious, or ASC. Begin with looking up the different brainwave states all humans cycle through each day. It begins with Beta, then Alpha, Theta, Delta brainwave states. A simple google search can tell you more about them, though I will mention that light meditation is more for the Alpha brainwave state, which is easier to get into when starting from a Beta brainwave state. Deeper meditations hit up more trance like states (which is arguably the state easiest for full on projection).
Pathwalking tends to be more projection to a specific subtle realm (with the context that realms are within the planes of existence that are specific to each culture, religion, and spirituality). While you can enter trance by the typical method of meditation, you can also do so by things like sensory deprivation, entheogens (not suggested if you don't know what you're doing), rhythmic movement, and even going to a place physically that resonates with the subtle realm you are trying to reach.
An example of this is how I visit pine trees and forests to help me better connect to the surface of the Nordic realm Svartalfheim. While it is not explicitly stated in the lore that Svartalfheim's surface has pine forests, I find this to be a personal truth. Another example is by having a bonfire to aid in traveling to the Nordic realm of fire giants, Muspelheim.