Prayer is communicating with God, it is the key to unlock all locked doors. It is one of the factors that helps one to overcome temptations and hence stand firm in Gods' word.
However, Giving is the crucial thing in the life of a Christian. It is the art of showing your faith and belief in the word of God. Without giving to God even if you are a prayer warrior, nothing will come on your way, or nothing will be answered.
You justify yourself to God through giving. Your faith is tested by giving and if you don't give then you don't have faith in God. Abraham's faith was tested through giving, where God commanded him to sacrifice his only son for him, it was after that incident that he was crowned the father of faith.
For you to be blessed as a Christian you must give. Giving is the only way to receive Gods' blessings. In Luke 6:38, give and it will be given to you, a good measure, pressed down, shaken together and overflowing will be put into your bosom.
In Malachi 3:7-10, give full tithe to the Lord so that His house is full of food and you will see God being tempted to open heavenly windows so that blessings are poured down to you and you will be called blessed one.