Know the reason
Understand the reason to become Christian. If you are converting from another religion or faith then it is very important that you have strong reasons to become Christian. There could be the level of practice or some fundamental things which you dislike for any particular religion and that has pushed to change the faith all together. You should know the all possible things about your previous believe when converting it to another religion as well.
Read as much as possible
Reading about any subject or thing even about religion will help you know and give the better understanding what you are going to do in near future. Also read some renowned scholars teachings regarding the religion you are going to adopt.
Read the bible with detail
Read the bible in detail and become familiar with teaching of Jesus. According to the bible teaching everyone is a sinner and born with sins."If you look upon a woman to lust, then you are guilty of adultery already" (Matthew 5:27-28). "If you hate your brother, then you are a murderer" (Matthew 5:21-22). This will guide you to overall understanding of the religion.
Believe that Jesus died on the cross
As Christian should believe that Jesus died on the cross and he died for all humans’ sins. This belief makes you a good Christian as Jesus rightfully died on the cross as God was also with him at every step.
Express repentance to God
Express repentance to God and ask for his mercy. This is important that you feel that God almighty gives everyone all the sufferings and happiness in their lives.
Express reliance upon God
Express reliance upon God and specifically give yourself to him as he is the ultimate protector and saviour in this world and here after.
Be baptised and continue to spend life as you have been given a new life. Carefully took every step and make sure you do not repeat mistakes.