Reading on Prayer

yep. with theology books you can know about God. with prayer you can actually know God.

Is that Nicholas Cabasilas's "Life in Christ"? Or a different text by the same/similar name? I've been meaning to read it - one book I have keeps mentioning Cabasilas and every time I hear something from him or from this text I'm very impressed

Yes, Holy Fathers spoke a lot about prayer. I won't reiterate quotes upon the topic since your text is very good.

However, I think that most of the time we need a little order in our knowledge. Of course, we must be careful to not over-analyze the topic, however we must touch it just enough in order to help us better.
There are several types of prayer according to their way of doing them and other types according of their intent.
The most powerful one is Jesus' prayer for which we should use a prayer rope.
Also, we must know a little about the positions during prayer, our disposition and how to avoid the wandering of the mind. Tied closely to this is the problem of using images during prayer.

There is a lot to say upon this, but I think that the above is enough as a starter pack. Besides that, what matters in prayer is quality but this comes through quantity.