Know your audience.
Remember, many people you know or meet for the first time have no Christian background at all. This means that the way we answer questions may be very different than people who have never been to church or those who haven't been since they were kids. Unchurched people don't have the same predispositions that we have, which means we can't go around quoting Bible verses. Always be slow and careful to communicate by knowing who you are speaking with.
Be honest and intentional.
This is the key. You must have this down before you enter into a spiritual conversation with anyone. Think before you speak and choose your words carefully. Never try to force someone into having a conversation they're not ready for.
It's important that you get to know where people are on their spiritual journey before diving in. Don't assume that they're ready to hear about the whole God and Jesus thing upfront. While, yes, it's important to share the good news of Jesus, you need to know more about the person you're speaking with so you don't hurt or offend them. You can start by asking about their past: Where did you grow up? What was your home life like? Did you ever go to church? And follow up by asking questions about their present: What makes you curious about God now? Have you done any reading to discover what you think or find appealing/frustrating? What questions do you need answered now?
It's important to spend time in prayer before you speak with the person as well as asking for God's help while you are with them. *Pro-tip – don't say it out loud, you may freak them out.
Avoid churchy language.
Once again, remember who you're speaking with and avoid throwing scripture at them or terms they might not be familiar with. Phrases like "sinner", "God put it on my heart", "a spirit of heaviness", "share your testimony", "born again", "saved", etc. can deter someone from diving deeper into a conversation with you. People outside the church have no clue what these phrases mean and this can be offputting toward those who may have been hurt by the church in the past.
Keep it relevant.
When Paul spoke to the Gentiles in Acts 17, he didn't use scripture. To Athenians, he quoted their own poets. Don't be afraid to use modern films, literature, and philosophy in your responses or as illustrations.
When we face tough questions, there are two helpful things to ask ourselves. First, why would someone ask this? Second, what question could I ask in response? As Aaron Burr says in Hamilton, "Talk less. Smile more." For a lot of people, even asking a question can be a big emotional step. So we should listen and affirm their questions.
Let God do the work.
There is a difference between knowing God and showing God. The goal is not to win arguments, it is to win people to Jesus so their lives will be changed. Do NOT use manipulation as a way to persuade people to Jesus. Love them, pray for them, and keep the conversation open for as long as it takes. And remember, we may never see their conversion on this side of heaven. And that's ok, it doesn't mean God ever stops working.