Shaykh Yasir Qadhi acquaints us with the next aspects of Tawassul that can make our duas to Allah.
One of the most powerful mechanisms to make a dua is by using the Names of Allah while making dua to Allah so as to invoke effectiveness of the dua.
Two Names of Allah applicable in any dua that are equally valid - Allahumma and Rabbana.
The dua made by Zakariyyah AS for a child is the best example of using the appropriate name of Allah -
وَزَكَرِيَّا إِذْ نَادَىٰ رَبَّهُ رَبِّ لَا تَذَرْنِي فَرْدًا وَأَنتَ خَيْرُ الْوَارِثِينَ
O my Lord! Leave me not single (childless), though You are the Best of the Inheritors.
[Surah Ambiya, 21:89]
It is also acceptable to let someone of a high status of piety, righteousness and religiosity to make dua on our behalf.