The basic idea behind most forms of meditation is to turn inward, to pay attention to your inner self and center your consciousness so that your mind is open and clear. During meditation, the purpose of this inward looking is to remove all outside distractions and quiet the chatter inside your head so that you can hear the voice of God.
Prayer is essentially the exact opposite of meditation. During prayer, you clear your mind of all outside distractions in order to be able to focus your thoughts on the prayer itself and the answers you hope to find by praying. In essence, we meditate so that God can speak to us; we pray so that we can speak to God.
Every religion known to man instructs believers to have faith in a Higher Power to listen to their prayers. They instruct you to be confident that everything that happens in life, as it is orchestrated by that Higher Power. Because of the faith that God takes care of everything in life, praying selflessly is considered to be the ideal way to pray. It is unnecessary to pray for oneself if God is in control and everything happens for a reason known to God. The stronger your faith, easier it is to direct prayers outward for others rather than inward for the self. For example, a person whose faith is uncertain or not fully developed may pray that God will relieve them from suffering or troubled times. But a very faithful person, who does not doubt the power of God, will consider that their own troubles may be a gift from God or a test to make them stronger in their faith and in their life. As a result of this recognition, faithful people will probably send prayers to God for others to be relieved from suffering. Spiritual growth depends on having faith that God will take care of you, and therefore spend time praying for others, selflessly.
To practice prayer meditation, sit quietly and center yourself as usual. But instead of focusing on clearing your mind, imagine yourself praying to God. Witness your prayer silently, objectively, without comparisons or judgments, and then say a prayer to God for yourself. Say a prayer for another person. Pray for everyone you know, and everything in your life. Continue praying steadily - ten times, a dozen times, or however many times it takes for you to feel as though you have prayed enough.
By actually witnessing yourself praying, objectively from the outside, you will discover that praying for others makes you feel good about yourself. So by practicing prayer meditation, you are simultaneously praying for other people while you are opening your inner self to the blessing of God making you happy and taking your troubles away. Combining prayer and meditation is the best of both worlds.