Keys to open up the human heart (in the Holy Spirit's guidance) to allow Jesus to get into [an] enquirer's heart & do/finish the business that He is already doing in the person's life by drawing him/her to Himself sometimes over many years - to the point of your "God-instance"/encounter. NB Conversion is always essentially/a personal meeting with Jesus. 

① Goodness & kindness (2 Tim 2:22-26

② Be real/show courage/take risks/to reveal God's love & joy (2 Cor 3:2-3

③ Be natural/be profound without at the same time being "heavy"/ - be real listen to God carefully/closely & learn to ask the right enabling/opening up questions. 

④ Always show natural/free/spontaneously wholesome humour (love/joy/humour(laughter) from the very heart of God - truly redemptive / reconciling) 

⑤ Listen without reaction/judgement 

⑥ Talk good sense - building up confidence & faith/trust in the listener John 8:32 

⑦ Speak creatively/affirmingly/things over people show naturally God's love affirming/encouraging them. See the image of God in people always. Loads of people don't naturally feel good about themselves. ...poor self image/low self esteem/worth
...root lack of security significance & self worth
They don't really love themselves/start to really love themselves until they know God truly loves them in Jesus.

God-instances occur as we know our role to discover where the Holy Spirit is working in people's lives. This needs our faith & obedience. We should be midwives, not salespersons in our role as Christ's ambassadors.

God prepares people for encounters with Him when He (the ultimate mystery here) knows beforehand [who] will respond to His grace.

Keep prayerfully looking for such "Cornelius" type people in the world (in who[m] God is already working (more or less consciously to them) - sometimes for a long time/even all their lives (did they/we but know it).

Go through life prayerfully & in action always with a spiritual thermometer (by the Holy Spirit).