1. You should give the new Muslim the feeling that Islam is a perfect religion, its source is divine, and it is totally inclusive. You have to emphasize that there is no truth but the truth of this religion.
2. You should clarify to the new Muslim that Islam erases every sin before it. Otherwise, he will keep thinking about his previous sins. You should make it clear for him that the moment he converted to Islam, his records became clean,
3. Assure him that the only reference for Islam is quraan and sunnah, not the wrongdoings of Muslims. Only Quran and Sunnah can define what is right and what is wrong.
4. Advise the new Muslim to read Quran, Hadith and Seerah (life of the Prophet Salalahu Alayhi wa Slaaam) as often as possible.
5. Advise him to take care of his personal cleanness in all its types, (Ablution, Ghusal etc.)
6. He should perform prayers in time, and you should point out the importance of praying in Jamaat Congregational Prayer-For Sisters it's more reward at home, but if you wish to pray at the Masjid, you are free to do so).
7. It is very important that the new Muslim lives in an Islamic environment. This will help him to obey Allah, mainly by keeping him away from sins, and wrongdoings.
8. Take the new Muslim to a nearby mosque. It is better to have someone from the neighborhood accompanying him and following his progress.
9. Let the Imam of the mosque know about this new Muslim, and remind the Imam to take special care of him.
10. Advise him to read and learn more about Islam. It is better if he can dedicate some of his time to do that, whether by himself, or with a group.
11. It is very important for the new Muslim to ask about everything he does not know or can't understand. He should try to contact scholars or at least ask anyone he trusts.
12. Try to know about his financial status, and help him as much as possible to make him feel friendlier. It will be more encouraging to have his salary raised a little, if you are in a position to make that possible.
13. You should make it clear to him, that his conversion to Islam would cause him some problems. Allah is testing his faith by these problems. He can always handle these problems by referring to Quran and Sunnah.
14. You should emphasize the importance of Monotheism and Islamic belief basics. You can provide him with a book that explains these important things in a simple way.
15. Try to keep him away from his previous atmosphere, and to involve him in an environment that suits, and helps his development as a Muslim.
16. Try to engage him in some Islamic activities, and provide him with important books and recorded lectures.
17. Try introducing him to group from his nationality. The communication between them will be easier; he can also have lessons with them.
18. He should feel that he is important and loved by everyone, because of his conversion to Islam. Giving him a gift would be a good start
19. Make it clear to him that the problems he faces have occurred to every new Muslim, so they are expected. Try to follow-up with his problems, and help him solving them, so that he can handle them without doing something terribly wrong.
20. There should be a simple approach that helps him to learn Arabic language (reading and writing), In order to be able to read Quran by himself and understand it.