I just posted this in another tread and it fits here as well.
I believe there are several "rules" which must be followed in asking something in prayer.
1) We must ask "in faith" and "in confidence." James 1:6 "But when he asks, he must believe and not doubt, because he who doubts is like a wave of the sea, blown and tossed by the wind." We should have confidence that God will hear us and respond. 1 John 5:14-15 "This is the confidence we have in approaching God: that if we ask anything according to his will, he hears us. And if we know that he hears uswhatever we askwe know that we have what we asked of him."
Which brings us to Point 2) We must ask according to God's will. James 4:3 "When you ask, you do not receive, because you ask with wrong motives, that you may spend what you get on your pleasures." Even Jesus prayed for the Father's will to be done. Matt. 26:39 "Going a little farther, he fell with his face to the ground and prayed, 'My Father, if it is possible, may this cup be taken from me. Yet not as I will, but as you will.'" The Lord will not give what he knows not to be in our best interests, whether short-term or long-term.
3) We should be specific in what we ask for. There are plenty of examples but here is just one- James 1:5 "If any of you lacks wisdom, he should ask God, who gives generously to all without finding fault, and it will be given to him." Thus your prayer is focused rather than rambling. A prayer such as "Lord, please provide the means for me to make my house payment this month" is much more likely to be answered positively than "Lord, help me win the Lottery this week."
I hope this helps, and I pray that God will help you figure it out.