Communicating with spiritual beings

First, the most important thing to understand is that knowledge is power. Knowing what your looking for, of who you want to speak with, sets up an ease of communication- as it's not hard for a demon to mascaraed as a ghost if you don't seek out a particular ghost. At the same time even when your looking for something or someone it is hard to know if you've truly found who or what your looking for, this falls upon your own instinct and knowledge as a practitioner of magic.

Catalyst: A Catalyst is any item that is clear or reflective. Such objects could be the screen of a tv or phone, a bowel of water, a glass ball, or a mirror. Any of these objects work.

Firstly, if you know who your looking for - god, ghost, or demon, speak it's name to get it's attention. In the case of a god or demon, an offering to it is customary - however in the case of a ghost they generally do not require such.
If you do not know who your looking for or your simply looking around (This is ill advised) then simply state your name as "I am ___", once you declare your name ask if anything is near clearly, do not falter when addressing an entity you do not know.

In either case, if your given a response in the form of a chill down your spine or a shadow in the surface do not look away, taking your eyes off it will break the spell. Concentrate to hold the being there but do not force it to, if it begins to resist let it go by looking away.

Clarify who they are or ask who they are clearly, it will take time time and more time for an object to actually appear but, in many cases, they will project an image into your head. This is a sign that the channel is made. The first time is always the hardest, so, after this contacting the same being may not be as hard.
Gods and demons, after reached with this method, should be easier to pray to and gain responses.

Once your done speaking with the being formally state "I, (your name), ask that you leave me now." If they persist and stay then state "I demand you leave." and break eye contact with the object.

Over time you'll be able to ask yes and no questions and get results as images of the words 'yes' or 'no'. If it is about the future then you may see a brief image or symbol. Over time the conversations will be more clear and easier.