Helping new believers grow
As newborn babes, desire the sincere milk of the word, that ye may grow thereby:
1 Peter 2:2 (KJV)
A newborn needs care straight away, and so does someone who has just received Christ. Winning a soul includes staying close afterwards.
Reach out within 48 hours. A call or a message tells them they are not alone.
Help them understand what happened. Go back over the Gospel, and show them from scripture that they are saved.
Get them into the Word and prayer. Start them on the daily devotional, and read it with them where you can.
Bring them into a church family. The first believers continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers. Faith grows best among believers.
Guide their next steps. Teach them about water baptism and being filled with the Holy Spirit, and show them how to share their faith.
Then update their follow-up status, so that nobody is forgotten.
Say it simply
Call them quickly, ground them in the Word and prayer, bring them into church, and keep walking with them.