The Etiquette of Du'â

To abstain from haraam food, clothing and earnings. (Muslim : Tirmidhi)
To make Duaa with sincerity. In other words, one should firmly believe that nobody but Allah Ta'aala will fulfill his objectives. (Haakim)
One should perform a good deed prior to making the Duaa & he should mention this during the course of the Duaa. For eg. He should say, O Allah! I had performed so & so deed solely for Your pleasure. O Allah! accept my Duaa due to the barkat of that deed. (Muslim, Tirmidhi, Abu Dawud).
To make Duaa whilst one is paak & clean. (Tirmidhi, Abu Dawud, Ibn Majah, Nasai, Ibn Hibbaan, Mustadrak).
To make wudhu before the Duaa (All six major hadith collections)
To face the Qiblah (All six major hadith collections)
To sit as in the Tashahhud position (Abu Awanah)
To praise Allah Ta'aala at the beginning as well as at the end of Duaa (All six major hadith collections)
To convey Durood upon Rasulullah (saw) at the beginning as well as the end. (Abu Dawud, Musnade-Ahmad)
To spread out both the hands. (Tirmidhi, Mustadrak)
To raise both the hands up to the shoulders (Abu Dawud, Musnade-Ahmad)
To sit with humility and respect. (Muslim, Abu Dawud, Tirmidhi, Abu Dawud)
To mention ones helplessness and dependence. (Tirmidhi)
To abstain from raising the eyes towards the sky whilst making Duaa (Muslim)
To mention the Asmaal-Husnaa (the names of Allah Ta'aala) and the sublime qualities Of Allah Ta'aala. (Ibn Hibbaan and Mustadrak)
To abstain from ceremonies rhyming of the Duaa phrases (Bukhari)
To abstain from saying the Duaa in a "sing-song" tone if the Duaa is in a poetic form (Hisn)
One should make Duaa through the medium of the Ambiyaa (alayhimus-salaam) and other Pious servants. (For eg. He should say. O Allah! Accepts my Duaa through The good offices of these saintly people). (Bukhari, Bazzaar, Haakim)
To make the Duaa in a soft voice (All six major hadith collections on the authority if Abu Musa)
To utter the Duaa phrases transcrIbnd from Rasulullah Sallalahu Alayhi Wasallam because Rasulullah Didn't leave out a single need of the Deen nor of the dunya whilst teaching us how to make Duaa (Abu Dawud/Nasai)
To make a Duaa that encompasses most of the needs of Deen and the dunya. (Abu Dawud)
To make Duaa in favour of oneself first, thereafter ones parents and to include the other Muslims in the Duaa as well (Muslims)
If the Imam is making Duaa, he should not make Duaa for himself only but he should Include all the congregants in the Duaa (Abu Dawud, Tirmidhi, Ibn Majah)
Abu Dawud (R.A.) Narrates that Rasulullah Said that the Imam who makes Duaa for himself only, has betrayed the people." In other words, the Imam should not Make a Duaa that is restricted to him alone. For eg. He should not say, "O Allah! cure my son." or "O Allah! Return my lost item." etc. but he should make a Duaa that includes all the congregation for eg. He may say "O Allah! Forgive us and have mercy upon us."
To make Duaa with firm conviction (for eg. he should not say: "O Allah! If you wish fulfil so and so task of mine." (All six major hadith collections)
To make Duaa with enthusiasm & yearning. (Ibn Hibbn & Abu Awana).
As far as possible endeavour to bring about a "presence of heart and mind" and cherish a high hope of the Duaa being accepted.(Haakim)
To make Duaa repeatedly. (Bukhari, Muslim)
This repetition should be at least thrice (Abu Dawud)
Note One may repeat the Duaa thrice in none sitting or he may repeat it on three different occasions. The "repetition of the Duaa" can be interpreted in both ways."
To make Duaa earnestly and insistently. (Nasai, Hakim, Abu awanah)
To abstain from making Duaa of severing family ties or other sins. (Muslim, Tirmidhi)
Avoid making Duaas of pre-determined and fixed things (for eg woman should not make a duaa of being
transformed into a man or a tall person shouldn't make Duaa thus:"O Allah! Make me short ." etc) (Nasai).
Don't Make Duaa for impossible things. (Bukhari)
Don't make a Duaa in which you ask Allah Ta'aala to confine His mercy to yourself Only (Bukhari, Abu Dawud, Nasai, Ibn Majah)
Ask only Allah Ta'aala alone for all your needs. Do not depend upon His creation. (Tirmidhi/Ibn Hibbaan)
The one making the Duaa as well as the person listening to it, both should say Aameen at the end. (Bukhari, Muslim, Abu Dawud, Nasai)
Rub both hands over the face at the termination of the Duaa (Abu Dawud, Tirmidhi,Ibn Hibbaan, Majah, Hakim)
Don't be impatient over the acceptance of Duaas. In other words, don't say: "I've made Duaa repeatedly but to no avail." (Bukhari, Muslim, Abu Dawud, Nasai, Ibn Majah)