His Word or His Will?
The easiest way to get answers to prayers is to pray the will of God. But that is where the problem is because the word of God is not always the will of God. The word of God wants us to pray for all men.
1 Timothy 2:1 KJV
 I exhort therefore, that, first of all, supplications, prayers, intercessions, and giving of thanks, be made for all men;
That is clearly the word of God. But in some situations, the will of God might be different. For instance, look at what 1 John 5:16 says.
1 John 5:16 KJV
 If any man sees his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it.
In this particular scenario, Paul says do not pray for a person who has sinned a sin unto death. Moses experienced the same in Deuteronomy 3:25-26.
Deuteronomy 3:25-26 KJV
 I pray thee, let me go over and see the good land that is beyond Jordan, that goodly mountain, and Lebanon.
 But the Lord was wroth with me for your sakes, and would not hear me: and the Lord said unto me, let it suffice thee; speak no more unto me of this matter.
Rather than just praying general prayers, God values it more when you pray specifically according to his will. That is why 1 John 5:14 says:
1 John 5:14 KJV
 And this is the confidence that we have in him, that, if we ask anything according to his will, he heareth us.
Notice The bible says if you pray in accordance with his will not just if you pray in accordance with his word. A person skilled in prayer will ask the Lord. "Show me your will about this matter so I can pray in accordance with your will".
Anytime I struggle with getting an answer to a prayer, I stop and ask the Lord, "am I praying what you want or am I insisting on what I want yet trying to get you to answer the prayer?"
Learn to ask God "what is your will?"
For example, don’t pray lord I want to relocate to Japan because I see great business opportunities there. Rather, ask the lord please let me know what your will is. The lord will let you know by giving you a signal of peace in your heart. When you get an inner peace on a matter, you can then pray for it.