Start with this Du'a
Before intimacy: keep Shaytan away from us
بِسْمِ اللَّهِ، اللَّهُمَّ جَنِّبْنَا الشَّيْطَانَ، وَجَنِّبِ الشَّيْطَانَ مَا رَزَقْتَنَا
Bismillah. Allahumma jannibnash-shaytan, wa jannibish-shaytana ma razaqtana.
“In the name of Allah. O Allah, keep Shaytan away from us, and keep Shaytan away from what You grant us.”
Sahih al-Bukhari 141, Sahih Muslim 1434
'What You grant us' refers to any child Allah (SWT) may decree.