Atheists are human beings -- indeed, many may very well be future converts in waiting. There are two sorts: the intellectual (weak), and the volitional (strong). The latter you will have no luck with; the latter Aquinas, Clement, Origen, Calvin, and Jesus had none as well. It is the former we must focus our attention. Given that atheists are human beings (many Christians fail to see this), what unites us is unity of attention; read the same books as them -- pick up Nietzsche --, try and comprehend their perspective towards life; and most importantly, be yourself. It is the intellectual sorts such as these that are keen at recognizing superficiality and artificiality -- both are the emissions of Christians who try too hard; in their process of missions they fail to see the subjects as people. Love people. Pray for love; pray for honesty; pray for impartiality. These three things -- the first being paramount -- are what people are drawn to; such it was with Jesus, and such it is with His disciples. Also, do not be overzealous, anxious, or condescending. Love is patient, the apostle tells us in the thirteenth chapter of his epistle to the Corinthians. Condescention may sneak in involuntarily, via the quoting of scriptures regarding judgment or rebuke. Eschew such manners. Theological doctrine is not the center of your appeals; Christological doctrine is, and such is revealed through action; theology comes later.
I wish you the best of luck. I find that coming to such a place as this has revealed the true hearts of those I have otherwise considered arrant rebels. Some of the greatest of skeptics came to be known as the most profound of Christians. Only after their conversion did they come to realize that all the vexation involved with the truth was indeed a progression -- and not a revolt -- towards the absolute. So it goes with us all. As Pascal once said, the heart has its reasons that its own mind knows nothing of. While this is magnificantly true, it must be known that the heart is accessed first through the mind, and the comprehension that entails it. This is your job -- and quite an exhilerating job it is. Read C.S. Lewis, Chesterton, and anyone profound in regards to apologetic literature. Great modern day thinkers include Peter Kreeft, J.P. Moreland, William Lane Craig, Dallas Willard, R.C. Sproul, and Ravi Zacharaias. I personally recommend the first two -- with Lewis and Chesterton.
Again, the best of luck.
Blessings.