If we say that we are doing da'wah, then it means that it as an act of striving, working, doing, and any other verbs indicating the act of da'wah by any means possible, to change our environment, to change others and most importantly, to change ourselves. Despite giving it our all for the sake of da'wah, a da'ie must not forgets that the result will only depends on Allah's help and will.
Rasulullah, Muhammad s.a.w. during The Migration (Hijrah) asked the help of a guide for the best route to Madinah, despite praying to Allah for His guide and favour for a successful journey. He and Abu Bakar hid in the Cave of Thur, on their own thought, and Allah helped them by commanding the spiders to build their webs around the entrance of the cave so that their pursuers would not notice them. Before a war, for instance, Muhammad s.a.w and his companions will get ready, preparing the swords and suits of armor and at the same time pray that Allah will send his army of angels to win the battle.
The believers must give something for the sake of da'wah so that the process will be much easier. In this case, praying and seeking the help from the utmost Creator is a necessary act so that da'wah will be much easier. Nevertheless, Allah's help cannot be regarded as 'miracle from the heavens' as we need to put our own blood and sweat into it first. We need to regard the help from Allah as a respond from Him based on our effort to do our best for da'wah.
O you who believe! If you help (in the cause of) Allah, He will help you, and make your foothold firm. (47:7)