Tawassul means seeking intercession to Allah The Almighty by means of His beautiful Names and supreme attributes in response to His Saying (what means): {And to Allah belong the best names, so invoke Him by them.} [Quran 7:180] Call upon Him by His Names: The Generous, The Beneficent, The Munificent, The Accepter of repentance, The Forgiver, The Powerful, The Free of Want and The Omnipotent. Call upon Him by those names, sing His praises by them, raise your hands towards Him with those supplications, and approach Him wholeheartedly.
The plea by means of the beautiful Names and supreme Attributes of Allah is one of the means by which Allah The Almighty responds to supplications. It is like, if not better than, seeking intercession by one's righteous deeds. The plea by the righteous deeds was strong enough to remove the rock, as we know in the Hadeeth (narration) of the rock which filled the opening of the cave upon the three men, and it was narrated by Al-Bukhari and Muslim. It is thus more fitting to make Tawassul to the Lord by His beautiful Names and supreme attributes, and affirming His Oneness, in order to ensure the Response to his supplication.
To give in charity, along with making supplication, is one of the means by which the Lord responds to it, as we have already mentioned. This was the conduct of the Prophet . Whenever they set out to perform the Prayer of Istisqaa’ (prayer for rain) or any other matter in which they gathered together for supplication, they would give in charity and come out in a state of abject humility before Allah The Almighty, offering themselves submissively to Him, thereupon Allah The Almighty would respond to their supplication. "Secret charity extinguishes the Anger of the Lord Almighty." [Saheeh Al-Jaami‘] as stated by the Messenger of Allah . Charity is one of the righteous deeds by which the supplication rises to Allah The Almighty as confirmed by Allah The Almighty when He Says (what means): {and righteous work raises it.} [Quran 35:10]
If you would like to raise a good deed to Allah The Almighty, be it a supplication or Thikr (remembrance of Allah The Almighty), raise it with the righteous deeds. Charity, given in secret or in public, is one of the righteous deeds, by which supplication rises to and receives answer from Allah The Almighty.
If, after all of this, the supplication happens to include the greatest Name of Allah, as narrated on the authority of the Messenger of Allah then, it is most likely that the Lord Almighty would respond to it. The Messenger of Allah heard a man supplicating: "O Allah! I ask You O Allah, by Your being The One and Only, The Eternal Refuge, who neither begets nor is born, nor is there to Him any equivalent." On that the Prophet said: "He (this man) has invoked Allah by His greatest name by which, if He is invoked, He would respond (to supplication), and if He is asked (anything), He would give." [An-Nasaa’i]
Anas, may Allah be pleased with him, said: “I was sitting with the Messenger of Allah while a man was supplicating, ‘O Allah! I ask You by the fact that all perfect praises be to You: there is none worthy of worship except You, The One who confers favors and The Creator of the heavens and earth, The Owner of Majesty and Honor, The Ever-Living, The Sustainer of (all) Existence.’ On that the Messenger of Allah said: ‘He (this man) has invoked Allah by His greatest name by which, if He is invoked, He would respond (to supplication), and if He is asked (anything), He would give.’" [An-Nasaa’i]
If the supplication includes any of those narrated on the authority of the Messenger of Allah which imply the greatest name of Allah The Almighty, it is most likely that Allah The Almighty would accept this supplication; if he asks Him, He would give him, and if he invokes Him, He would respond to his supplication.