In the army I was the Commander’s Radio Operator for an Airborne Ranger Infantry Battalion. I would have been the first man that the enemy would target with that long antenna sticking up because I was the soldier that could call in the air support or reinforcements that would change the course of the battle and wipe the enemy out. I was the man on the ground that could call for help and was heard. The Battalion Commander and I stuck together.
Today, I am a prayer warrior which I find very similar to serving as the Radio Operator. (Sometimes I just feel like the canary in the coal mine). Fortunately I was trained by the best prayer warriors on the front lines between life and death. I have learned how prayers must be done to be heard. And yes, I am Catholic.
I understand that time operates differently in Heaven, on earth and in hell. We also primarily experience existence in a dimension that is spatial and continues through a finite time. I understand that the Word of God is creation and contains great weight. When God speaks things happen. If God were to speak directly to you, your fear would be automatic because you would have no choice.
I have heard the Word of God several times, perhaps not in the way you would think with my ears, but in the manner he speaks so that he may converse with me, not crush me with fear and permit me to chose to act upon his Word. As I said when God speaks, things physically happen. As such I pray to God and Heaven aloud to respect the way God speaks to us with a physical act. I am not enamored of silent prayer. He deserves more.
Praying aloud also helps me to focus on what I am praying. As I usually pray in English, sometimes Latin, and on occasion Aramaic, I believe what is common to those beings above us who do not need to utter sounds to communicate is a mental focus on the physical meaning of the words in the prayer. This is purposeful intent which I believe He hears. The words prayed are then not empty but meaningful and spoken as truth to what you believe. Such is the weight of purpose we owe God.
I understand a day to those in Heaven is like a thousand years to us, so the ability for our prayers to be heard requires our voice be persistent. I try to pray every day and repeat the same prayers so they are joined together and heard in Heaven. So that is 1000 days of prayer on earth for one day to be heard in Heaven.
When we pray the Lord asked for two or more of us to pray together which is why we include Amen (which means I agree) at the end of each prayer to make it two utterances. In the end we want our Lord Jesus to hear us.
I have also been instructed that for God to hear you when praying for others that you must be in a state of grace. That means you must be Baptized, and not in a state of mortal sin. But our will is weak, and we commit mortal sins all the time, many times without even giving it a thought. This is why He granted us the Sacrament of Confession and Absolution. You can still pray for yourself if not in a state of grace and even include prayers for other people but for those prayers to have an effect for other people you must be in a state of grace. So to maximize the effect of your prayers go to Confession as soon as it is available whenever you commit a mortal sin. If you are unsure about what a mortal sin is you can read up on it in the Daily Missal.

In general, what are the mortal sins?
Any of the Seven Deadly Sins:
Pride, Sloth, Gluttony, Greed, Lust, Wrath, Envy
Any Violations of the 10 Commandments:
Love God and only the one God, no other Gods before
Do not take the name of the Lord God in vain
Honor thy Father and thy Mother
Keep Holy the Sabbath Day
Do not murder
Do not commit adultery
Do not steal
Do not bear false witness
Do not covet thy neighbors goods
Do not covet thy neighbors spouse