Insha Allah this finds you in the best of health and Iman.
This is a very beneficial resource I found online, with several chapters on Duaa. Below is Chapter 1.
HOW TO URGE OTHERS TO MAKE DUAA
DUA AS RECOMMENDED BY QURANIC VERSES AND HADITHS
- Why our Duas are not answered
- Advantages of Dua
- Admonition in case Duas are not answered