On the LC, clerical prayers work a little differently than suggested in the Labyrinth Lord rules. Normally, a cleric or priest would pray for his spells in the morning, and use them as he could throughout the day. This is still possible, but is one of three options for a cleric.
Pray for specific spells in the morning, use them as you can throughout the day. The rule book method.
Pray for general support from your Creator in the morning, then choose spells to cast in the heat of the moment. This method allows for much more flexibility, but there is a 10-25% chance that the spell you receive in the heat of the moment is not the one you prayed for. God is not a gumball machine, you can't just put in a quarter and know that gum is coming out. You make your prayer and God will give you what you need, whether you think you need it or not.
Use a combination of options 1 and 2. Pray for some specific spells, and leave some points free for last minute requests.
This method also incorporates the spell point system I've devised, so picking spells is a little more strategic than usual.