Pretty much unless you are a mystic, you don’t really know what it is. Many have an understanding or view that is not based on personal experience. I’ve encountered those who are mystic outside of the Catholic faith and I’ve encountered them within the Catholic faith. Those outside of the faith do not have the assistance of the Sacraments and although I see many New Age mystics who have the Holy Spirit working in them, and operate very much like Christ from their hearts and in their works, it is the mind that can be easily manipulated by Satan, and thus many New Age mystics if some of them really are, have been steered into incorrect truths that Satan has twisted. There is something known as Lucifers Twist.
I have read Catholic writings on what is meditation, what is the correct meditation, what is a mystic etc, and as someone who is a bit more mystical and does a lot of communion with God and the Holy Spirit and eventually came back to the truth of Christ and the essence of Christ after I spent some time trying to understand what New Age was, I have to say, some stuff that is written by Catholics on these topics is ignorant in some parts.
To be honest with you, unless the writings are by a Catholic Mystic, I no longer read them.
Anyone can obtain a closer communion with God and I found the best way to do this was prayer and contemplation and seeking Christ more and more. The Holy Spirit was of a great assistance to me focusing on and reaching Christ, as was a lot of faith in Christ to guide me. Reading others ignorance was just plain heartbreaking. A lot of it was not based on experience or understanding. As there are those outside of the Catholic faith who have been steered away from the truth, there are also those in the Catholic faith who write trollop and keep Catholics stagnating. I would suggest you do a lot of reading on the subject of a Catholic Mystic. Now I personally stick to a few basic things:-
I read up on Mystic Saints and other Saints and there are writings such as by St John of the Cross and Teresa of Avila that might assist your understanding, which I think someone has quoted already.
My faith in Christ I hold onto very tight
I pray to the Holy Spirit regularly and I pray to Mary.
I check any interpretation with official Catholic interpretation.
I’ve read some stuff by religious people, and Catholic writers etc but some of the things these people have written is ignorant in some parts and some of it comes from their own opinion or views. Depending on the topic.
If you are interested more about Catholic Mysticism, then pray for spiritual gifts, always keep your focus on Christ, learn more and understand more about the Holy Spirit. A lot of Catholic writers overlook the Holy Spirit. And don’t take every Catholic article as gospel. Some people have a habit of writing what they think things are. So keep reading, don’t stop at the first article you come across or are advised to read.
So keep reading and seeking, and keep your focus on Christ and the Holy Spirit and Mary (she will assist you to know her son as you know).
God Bless,