[ALL PRAISES BE TO ALLAH]
Dear brothers and sisters there are some Important points to be kept in mind while doing dua.You should
1.Do dua with firm belief that Allah will listen to your duas
2.Praise Allah before doing dua
3.Invoke Allah with good names like Ya Hayyu Ya Qayyum
4.Send salat on Rasool salal laho aliehi wasalam before and after dua.Durood of Ibraheem which is recited in salah is better
5.Avoid haram earnings.Allah does not accept worshipping of people earning haram
6.Do dua with consistency.Donot give up if it is not being answered immediately
7.Not ask for wrong doings like success in lottery
8.Not do dua for breaking relations
9.Ask for the best option .For example if you are asking for Jannah do dua for jannatul firdous(the best status of Jannah) because Allah is capable of giving the best
10.Purify your dua from shirk and innovation .You must not invoke any one besides Allah swt and should invoke Allah directly.You may get guidance from duas of prophets and great believers mentioned in Quran and duas of Rasool salal laho aliehi wasalam from books of hadith and Sunnah.You should also do dua in similar manner.