What a fantastic question! I love talking about my faith with non-believers, it used to scare me a lot. I didn’t know any tools, or techniques or anything (still don’t actually). But as my faith began to become part of who I am, I come to relish opportunities to talk about the most important thing in my life.
The first thing that you need is to just know why and what you believe. It’s not enough to just know facts about something, but why do you actually believe it. Why do you believe it? How does it change you, or does it change you? These are important questions to sit with.
The other major part is you need Holy Spirit help. A close relationship with the Holy Spirit (it’s His work anyhow), is important. He is the one who opens up doors, He plants seeds, He waters, we just get to join in on the work. When you wake up, pray for an opportunity. Look for them, be vigilant, in a non-creepy way.
We need to love our neighbours (family, friends, roommates) unconditionally and with a lot of grace. Especially your roommates. Your roommates are going to get to know you in ways that no one else will. Be quick to forgive, quick to serve, find ways to love, and bless them, often. Could be that you know they are coming home late and won’t have energy to cook supper, leave them a plate from what you have made. Even if they aren’t thankful.
Be sure that you do not put on airs. Be open and honest with your questions, difficulties, but show how you work through them. Being a follower of Jesus is not going to guarantee that you have no problems like no financial problems. But leaning into who God is (a good Dad who takes care of His children), trusting in His provision, and watching how He provides is proof! It is how we go through difficulty, how we deal with life situations as they come up firm in our identity in Christ, is what will make people ask questions.
I think also, listen to their stories. We use a term called “Gospel fluency” (for an in-depth teaching look here http://wearesoma.com/resources/watch/gospel-fluency/) which is essentially, listening to other people’s stories and learning to hear how people are already seeking God. Then the next step would be to connect it to how the gospel answers how they are seeking God. In other words, what do people seek to provide them comfort, security, peace, and identity.
I don’t think there is any “method” that works necessarily. But to summarize, pray and fast often for opportunities, listen to the Holy Spirit, bless often, and listen to their stories. Hold back their hair when they puke, clean up after them, and expect no thanks in return.