Sometimes subject specific resources can be really helpful. There are a number of resources that will be helpful to you if you are studying Philosophy, either as part of your course or as your major discipline. 

Resources (books)

Introductory
Relativism - Feet Firmly Planted in Mid Air - Greg Koukl and Francis J. Beckwith
Escape from Reason - Francis Schaeffer
Love Your God With All Your Mind - JP Moreland 

Intermediate
Introduction to Philosophy - Norman Geisler
Baker Encyclopedia of Christian Apologetics - Norman Geisler
Christian Apologetics - Norman Geisler
The God Who is There - Francis Schaeffer
Mere Christianity - CS Lewis
The Universe Next Door - James Sire 

Advanced
He is There and He is not Silent - Francis Schaeffer
Philosophical Foundations for a Christian Worldview - JP Moreland and William Lane Craig
Warranted Christian Belief - Alvin Plantinga
Scaling the Secular City - JP Moreland
The Case For God - Peter S Williams
Reasonable Faith - William Lane Craig
The Gagging of God - DA Carson
The Rationality of Theism - Paul Copan and Paul K. Moser 

Resources (other)

Evangelical Philosophical Society here and their journal Philosophia Christi