Honest recitation of the shahadah once, in Arabic, in front of two Muslim witnesses, is all that is required for a person to become a Muslim.
I bear witness that there is no deity but ALLAH, Who is without partner and I bear witness that Muhammad (SAW) is servant and Apostle.
ALLAH is pure and all praise is due to ALLAH and there is no deity but ALLAH, and ALLAH is most great and no one has the strength of virtue and power to remain unexpended from sin, but with ALLAH who is high and venerable.
There is no deity but ALLAH, who is without partner, He is the owner and all praises are for Him, He grants and spurns lives and lives itself, He is immortal. The whole welfare and benevolence is in His hand and he is the omnipotent.
O ALLAH! Thee my Lord, there is no deity except thee, thee created me and I am your servant and I am upon your oath and promise till I have strength. I betake myself to thee for those evils which I conducted. I confess for thee for the blessings that are upon me and I confess my sins So forgive me because there is no one who can excuse the sins.