Bettenson, Henry Scowcroft. The Early Christian Fathers; a Selection from the Writings of the Fathers from St. Clement of Rome to St. Athanasius. London, New York,: Oxford University Press, 1956.
My first recommendation is a didactic book that will introduce you to some of the selected writings of the early Christian Fathers of the Church. These writings are primary source material translated into the English language. The themes of each writer varies, but some of the central issues include the Church, Eucharistic Theology, The Sacraments, Jesus Christ and His ministry, Scripture, early defenses of the Faith (Apologetics), The Trinity, etc. The title of the book is "The Early Christian Fathers," published by Oxford University Press. The selected writings range from St. Clement of Rome (+101 AD), St. Ignatius (+107AD), The Didache (50-100 AD), St. Ireneus (130-200 or 202 AD), St. Justin the Martyr (+165 AD), Tertullian (+225 AD) and others until St. Athanasius (+373).
Chadwick, Henry. The Early Church. Harmondsworth,: Penguin, 1968.
My second selection is a Church History book titled "The Early Church," (Revised Edition) written by Henry Chadwick (Penguin Books, 1990). This book has many specific details and good insight about the history of the Church. The book covers the relationship between Christianity and Judaism, factors for the growth of the Church, Monasticism, the papacy, the first five Ecumenical Councils, liturgical themes, the relationship between Church and State and specific figures such as, Saints Constantine the Great, Justin the Martyr, Jerome, Cyprian, etc. My advice is to be careful whenever reading a non-Orthodox historian. Although this book is a classic and a must for everyone to read, I did come across one important error. On p. 130 Chadwick writes that for the Church, "of one substance (homoousios) affirmed identity." The problem with this statement is the word identity. This term erroneously is applied to what the Holy Trinity has in common (homoousios), that is one essence, one action, one energy and one will. The word homousios itself means one essence or one substance (substance is a Latin term (substantia) that often has a materialistic undertone so essence is more preferable as conveyed in the Creed. Thus identity does not refer to homoousios but to the unique characteristics of each Person of the Holy Trinity which is called hypostasis. Here, the uniqueness of each Person is defined as follows; God the Father is unbegotten, the Son is begotten and the Holy Spirit proceeds from the Father. To sum up, using identity to define homousios is erroneous for the reasons mentioned above and because it was this misunderstanding that gave rise to the first Trinitarian heresy in the mid-second century called Modalistic Monarchianism or Sabellianism (Sabellius was one of the three main supporters of this heresy in the West - the other two were Prakseas and Noetos). Outside of this shortcoming, the book is a challenging and accurate account of the Early Christian Church.
Pomazansky, Michael. Orthodox Dogmatic Theology : A Concise Exposition. Platina, Calif.: Saint Herman of Alaska Brotherhood, 1984.
My final selection involves a dogmatics book written by Father Michael Pomazansky called "Orthodox Dogmatic Theology" (Published by the Saint Herman of Alaska Brotherhood in1994). This book is not a difficult read nor is it hard to understand and it gives the reader a good sense of the Orthodox Church's doctrinal beliefs. Some of the contents include, God and the Creation, The Providence of God, Concerning Evil and Sin, God and the Salvation of Mankind, The Holy Sacraments, Prayer, etc. As a final note, please read Bishop Kallistos Ware's book "The Orthodox Way" prior to reading this book. It will allow you to establish a good foundation to build upon via this and future readings.