1. Be Humble
Oswald Chambers said that prayer is an effort of will. Prayer takes effort to be effective, but it is a journey worth walking. The first step is humbling yourself and confessing your sins. In Luke 18:9-14, Jesus told a story of a religious man and a tax collector, the financial swindlers of the day. Which prayer was heard? The tax collector's, because he humbled himself and confessed his sin. "..everyone who exalts himself will be humbled, but the one who humbles himself will be exalted." Luke 18:14
Read Psalm 66:16-20 for the testimony of another effective prayer.
2. Have Love
Matthew 5:44 tells us, "But I say to you, Love your enemies and pray for those who persecute you." This command does not need explanation, but we often reject the simple. If a humble heart is required for effective prayer, what can be more humbling than praying for someone that has hurt us? Remember, no one said it would be easy - just effective.