As a disciple of Christ, I am called on to always be ready to answer anyone who asks me about the hope that I hold on to. And it is not just me, but all who call on his name who are expected to be able to do this (see 1 Peter 3:15-16). Below are some tips that may be helpful to you in being able to successfully give a defense for your faith.
1. Be a Believer: An essential step to being an apologist is that you have a relationship with God; that you are a follower of Jesus. If not, you will be trying to defend something that is outside of your experience.
2. Be Active in your Faith: It will be very challenging, and not too effective, to share the reasons for your faith if you are not personally living it. You really need to believe, and be obedient to, the truth you are trying to defend.
3. Know What You Believe: Can you explain to someone else what you believe? It is not enough to say that you hold to the doctrinal statement of your particular church or denomination. You are not really called to defend a doctrinal statement. You are called to give answer to anyone who asks you why you believe. And to be able to do that, you need to know what you believe.
4. Know Why You Believe What You Do: Knowing what you believe is really only a first step. You also need to know why you believe it. It is generally not sufficient to claim the belief because it is what your church teaches, even though it likely does teach that. It is much better when you can put into your own words just why you believe some truth about your faith.
5. Care About Others: An effective apologist needs to have a concern for the people that he is sharing with. Without that, your defense will likely be more of a sterile debate or an angry exchange. Genuine concern for the person you are sharing with will be evident to the other person, and will make them much more likely to at least give you a fair hearing.
6. Know Your Questioner: Who is it you are providing a defense to? Is it another believer who has doubts or an alternative view? Is it an honest inquirer who just whats to know why you believe what you do and is open to your response? Or is it someone who is just looking to argue and has no interest in what you have to say? Knowing who you are talking to should impact the way you make your defense, and whether you should even bother; the last given alternative is one that most are advised to avoid.
7. Don't Get Sidetracked: It never ceases to amaze me the direction that conversations about faith can take. And too often those detours really have nothing to do with the original discussion or question. Sometimes that is OK. But other times the detour was intentional; an effort to steer the conversation into an area that your discussion partner feels more comfortable debating.
8. Be Respectful: Do not attack the other person, belittle them, or act like they are stupid because they don't believe like you do. Respect them as a creation of God. And respect their right to hold to the beliefs they do. That they do not believe like you is not a reflection on your value or beliefs. Remember that they are not answerable to you, but to God. Treating them with dignity and respect is your best shot at having them give you an attentive audience.
9. Keep Your Cool: Remember to always maintain a gentle and respectful attitude in your defense. If you feel you are reaching a place where you can't do that, then its time to disengage. Lashing out may be just the response that your questioner is looking for. While by no means applicable to all, I have found that some of those who are interrogating you are like a small boy with a stick, poking at the lion through the cage bars, trying to invoke a response. Don't give them that satisfaction!
10. Know When to Quit: You need to stay aware of the effect your defense is having. If it is being productive, then by all means continue. But all too often you quickly reach a dead end and need to gracefully disengage. If you have been able to explain to your questioner what you believe, and why, and have done so with gentleness and respect, then you have accomplished what you are called to do. How they respond is not up to you, and you are not obligated to go over the same thing over and over, or chase them through every rabbit hole they go down as they seek to confuse you.