I recommend EA Koetting's Mastering Evocation video series (you can get it from The Pirate Bay last time I checked). It's very practical and fairly straightforward in covering the basics comprehensively.
Also The art of drawing spirits into crystals by Johannes Trithemius. This one is freely available.
And the YouTube channel Mind and Magick, which has a Mystery School playlist that goes over everything you need to have the proper starting knowledge. We should never assume we have such knowledge.
Also Lon Milo Duquette and Jake Stratton Kent's The True Grimoire.
You could look into VK Jehannum's blog.
Also, learn how spirit interaction looks outside the context of Western ceremonial magic. Your practice might be different, but the phenomenon of contact itself is similar: https://www.youtube.com/watch?v=j4zdIQqxzIU
One of the most important things to learn is that spirits are not human. This might sound obvious, but when we're starting out we often expect them to be.
They don't speak our language, and they don't interact with the world in the same way we do. They are for all intents and purposes, from our perspective, aliens. Funny how materialism has pushed us to create things like SETI and our scientists are trapped in an ever worsening state of cognitive dissonance making up excuses as to why we wouldn't have had contact yet, when in reality all they do is ignore all the contact we do have with the spirit world from the moment we're born, and certainly after we die. But I digress.
As the entity Ra demonstrated in The Law of One, contact with spirits requires an environment that is adequate for them to manifest in while adequate for you to notice them. This is accomplished through the use of trance states and ritual paraphernalia.
Ritual trappings are technically not necessary, as an adept should be able to create the correct psycho-emotional state within himself in order to contact a spirit, especially if he's been in contact with that spirit before. However, it is more practical and easier to just use colored candles, incenses, lighting, etc., to create such a state within your mind and the mind of your ritual space.
The process of working with a spirit could be summarized as follows:
>get to know the spirit
Learn its correspondences, its history (objective) and myth (subjective or "fictional"). Read as much as you can about other people's direct experience with it.
>perform the ritual
Decide your intent beforehand, prepare your mental and physical space, and do the ritual. You don't need to make it up. There are plenty out there.
>learn to recognize how spirits communicate with you
It's very uncommon to receive spoken communication. It helps to think reality is a dream. You will feel you are one of those characters in Hollywood movies who think the TV speaks to them. Perhaps you will feel a voice is trying to speak from the depths of your mind that you can't quite make out no matter how hard you focus. You will see synchronicities in street ads, people's random words will make sense in the context of your ritual, etc. This can extend in time and space well beyond the ritual itself, and sometimes even occur before.
It's a wonderful journey. You wouldn't want to spoil it by approaching it too intellectually.