1. LISTEN - When people are debating or discussing issues of the Christian faith, both sides have to be open to listen to what the other side is saying. Firstly, the Christian must hear and try to extrapolate what the other person is questioning about and even try to understand the person's barrier to Christianity. The Christian should be willing to listen to the concerns of others instead of purely 'bible bashing'. Remember we have to act in love to our neighbours too. Also, the skeptic must be opening to listening to the stance of the Christian. Often I hear skeptics who argue against Christianity but don't really listen to what the Christian is saying, because he/she has already formed a notion that Christianity doesn't work, which means he/she is moreso trying to push his idea onto others instead of impartially discussing the topic.
2. STAY FOCUSED - More often than not, debates around religion centre around the premise of the idea of a divine being (a god), the compatibility of science and religion (evolution vs creation) and the evidence of Jesus' resurrection as prime examples. While usually discussions tangent off to very particular and specific questions of philosophical/moral/theological/etc. issues, we must remember as Christians to focus on the Christian belief we are trying to describe, and bring things back into perspective to the core values which we hold on to as Christ followers. While its good to delve into those specific issues, we must always remember and focus on the bigger picture of what Christianity is all about.
3. BE CONCISE - While we aren't all trained theologians, it is a really wise decision to familiarise ourselves (as Christians) with concise answers to commonly asked questions about the Christian faith. It is beneficial to know our testimonies, know the truths that Christians hold on to and cannot let go of, and to be able to explain these things in a concise and understandable manner. This prepares us for situations when we are able to explain and defend our faith.