Prayer as an act is meaningless. If we pray with some expectations, it is better to remain silent. Because when attitude goes wrong, everything that works around is not right.
If our attitude is prayerfulness, worshiping everything in life, then the prayer is meaningful. Realizing Brahman in ourself and becoming prayerful is a prayer.
During prayers, we should have full awareness of who are we. Our Mind should sync with heart, from concentration(Ekagram only one thought) to Meditation(and becoming that itself). If this continues, we will realize we are the one pervading everywhere.
God cannot do/give anything for us,unless we do something. What He needs to give has given enough. It is up to us to make use of it.
God has many forms and of course created by us for our convenience. Realized souls say ‘know about yourself’. Lord Krishna says, ‘You are born because of your karma’ . So do we need to pray God to increase our karma? or to surrender ourself to our Atman and attain Nirvana??