What Should we Pray for?
A: It is stated in the Srimad Bhagavatam that whether one is full of material desires, or has no desires, or desires liberation, one should approach the Supreme Lord Krsna. So whatever we want in life we should pray for Krsna to fulfill our desire.
It is of course not so wise to pray for material things as this will just prolong our stay in the material world. Best thing is to ask Krsna, "Please, take us out of samsara and engage us in Your pure devotional service."
Therefore we chant the Hare Krsna mantra. The Hare Krsna mantra is the supreme prayer because by chanting that mantra we ask Krsna to take us out of the material world and situate us in our original position of eternity, knowledge and bliss. So the Hare Krsna mantra is the best prayer you can offer to Krsna.
Here is a little anecdote.
There was an old woman who used to collect fire wood in the forest every day to sell in the market place.
She was carrying the fire wood on her head as is custom in India, but the wood kept falling off and she had to bend down and pick it up. This happened again and again. It was getting dark and she was getting very frustrated so in despair she called out for Krsna to help her in her predicament.
Krsna appeared before her and asked her what He could do for her. She said, that she would be grateful if Krsna could arrange it so that the wood would stay in place on her head so she could reach the market place in time to sell it before it got dark. So be it, Krsna said, and disappeared.
The morale of the story is that the woman was very foolish to cherish such petty desires. Here is the Supreme Lord standing right in front of her and she asks for such a ridiculous thing. Krsna can give us anything. Most of all He can give us pure devotional service so that we will never anymore have any problems in the material world. This material world is a place full of problems and misery, and as long as we are here, even if we live in very opulent circumstances, we are bound to have so many problems. So the best thing we can pray to Krsna for, is to take us out of this world once and for all, and situate us again at His lotus feet.