Thanks for your question. I think it is really great that you are wanting your friends to come to Christ,it shows that you have are concerned about their eternal destiny. I have a couple of thoughts that may help you.
Firstly, we can’t make anyone become a Christian. The Bible shows us that for people to cross from being slaves to sin to being slaves of righteousness is impossible. It is not something we can make them do nor is it something they can do by themselves. It is the work of God. Knowing this helps us not to undermine the value of praying for our friends. Further to this, the work of God is powerful. This helps us to know that no matter how resistant your friends maybe God can still work in them and turn them from their sin. You only have to think of the resistance that Paul showed towards Christians as he persecuted them to see the powerful work of God in his life. So, don’t undervalue praying for your friends - it is the first and most appropriate place to begin in wanting to see your mates come to know Jesus.
Secondly, people only become Christians through new birth as they encounter Jesus in the Bible. Jesus in his encounter with the Jewish leader Nicodemus in John 3:3 says that, “No one can enter the kingdom of God unless he is born again” and in v5-6, “I tell you the truth, no one can enter the kingdom of God unless he is born of wter and the Spirit. Flesh gives birth to flesh, but the Spirit gives birth to Spirit. You should not be surprised at my saying , ‘You must be born again’”. The Bible reinforces my first point about it being the work of God. It also reveals to us the person of Jesus Christ. Ultimately this is what you want your friends to grapple with. Who do they say Jesus Christ is? They don’t have to come to youth group to get to know Jesus - you could talk to them about Jesus or you could give them a copy of Mark’s gospel to read or you could point them at this website! Getting them to read the story of Jesus helps them to discover who Jesus is and to strip away any misconceived ideas they had about who Jesus is.
Thirdly, we are called to be people who live a beautiful way of life (1Peter 2:12 - a ‘good’ life). We know that salvation is the work of God but we are also to be a witness to the power of the gospel. Your friends seeing the difference that Christianity makes will cause them to give glory to God. And yes, this happens. I have just come back from lunch with someone who said he went away with some Christians on a camp and was astounded by their character and witness that he became a Christian over the course of the weekend.
Lastly, be patient and trust God. Patient that God will work in HIS good time as much as we would like Him to bea to our drum, he doesn’t. And trust God that he knows what he is doing with regards to your friends and their salvation.
I hope this was helpful,