Therefore I say to you, whatever things you ask when you pray, believe that you receive them, and you will have them. Mark 11:24
How do we know that God is a good God and a good Father?
Jesus dealt with this question simply by asking another question: "If earthly fathers, imperfect as they are, know how to give good gifts to their children, don't you think that your loving Father who is in heaven will be even better?"
If your child asks you for bread, would you give him a stone? Certainly not. You would give him the best bread you can find. How much more then will your heavenly Father give good things to you when you ask Him!
Know in your heart that God is a good Father to you. So if you need something today, just ask Him for it. And as you ask Him, believe that you have received it from Him, and you will have it!