One must first of all be faithful (sraddadhana). One must actually be very much eager to see God. Not that one takes it as a frivolous thing - "Can you show me God?" - or as some magic. They think God is magic. No. One must be very serious and think, "Yes, I have been informed about God. So if there is a God, I must see Him."
There is a story in this connection. It is very instructive, so try to hear. One professional reciter was publicly reciting the Srimad-Bhagavatam, and he was describing that Krishna is very highly decorated with all kinds of jewels when He goes to tend the cows in the forest. So, there was a thief in that meeting, and he thought, "Why not go to Vrindavana and plunder this boy? He's in the forest with so many valuable jewels. I can go there and catch the child and take all the jewels." This was his intention. So he was serious. "I must find that boy," he thought. "Then in one night I shall become a millionaire."
The thief's qualification was his feeling: "I must see Krishna! I must see Krishna!" That anxiety, that eagerness, made it possible for him to actually see Krishna in Vrindavana. He saw Krishna in just the same way as the Bhagavatam reader had described. Then the thief said, "Oh, You are such a nice boy, Krishna." He began to flatter Him; he thought that by flattering Him he would easily take all the jewels. Then he proposed his real business: "May I take some of these ornaments? You are so rich." "No, no, no," said Krishna. "My mother will be angry! I cannot give them away." Krishna was playing just like a child.
So the thief became more and more eager for Krishna to give him the jewels, but by Krishna's association he was becoming purified. Then at last Krishna said, "All right, you can take them." Then the thief became a devotee immediately, because by Krishna's association he had been completely purified. So somehow or other you should come in contact with Krishna. Then you'll be purified.