Practice what You Preach

But if our gospel be hid, it is hid to them that are lost II Corinthians 4:3

If you're talking about the Gospel you should be living by the Gospel.
Cause if you're telling somebody about how their sin is separating them from Jesus.
You need to be free from sin yourself.
Like the saying goes, "If you're gonna talk the talk, you need to walk the walk."

And show your own self in all respects to be a pattern and a model of good deeds and works teaching what is unadulterated showing gravity with dignity and seriousness. Titus 2:7 (AV)

You can lead others to Christ by example.
If they can look at your life, and see how living by the Gospel of Jesus Christ has changed your life, then they may start thinking I should (could) give this (Him) a try (trial). It can't hurt and its gotta be better than the way (how) I'm living now.
For unbelievers need to see, to believe.
Just like you did.
It was only after you came to trust in Jesus, that you learned to 'walk by faith and not by sight', so to must they learn.

Whom we preach, warning every man, and teaching every man in all wisdom; that we may present every man prefect in Christ Jesus. Colossians 1:28