What is the proper procedure for performing Sajda Tilawah?
You do a Takbeer and then go down into sajdah, and then you get up without saying a takbeer and there is no Tasleem, unless you are in salat when you would say a takbeer when you go down into it and come up.
When in the Sujood, you can say:
سبحان ربي الأعلى
Glory be to my Lord Most High, glory be to my Lord Most High
Also, the Dua' you say in the Sujood is:
سَجَدَ وَجْهِي لِلَّذِي خَلَقَهُ وَشَقَّ سَمْعَهُ وَبَصَرَهُ بِحَوْلِهِ وَقُوَّتِهِ
My face prostrates itself to Him Who created it and brought forth its hearing and seeing by His might and power
As well as:
اللَّهُمَّ اكْتُبْ لِي بِهَا عِنْدَكَ أَجْرًا وَضَعْ عَنِّي بِهَا وِزْرًا وَاجْعَلْهَا لِي عِنْدَكَ ذُخْرًا وَتَقَبَّلْهَا مِنِّي كَمَا تَقَبَّلْتَهَا مِنْ عَبْدِكَ دَاوُدَ
O Allah! Record for me, a reward with You for it, remove a sin for me by it, and store it away for me with You, and accept it from me as You accepted it from Your worshiper Dawood