Paraffin has some good ideas; what sort of entity you follow as a Cleric, or consult with as a Wizard is all up to you. The SRD and rulebook have some ideas in the respective class sections. The Cleric gets different Petitions depending on the precept of his/her religion, and the ways in which you can commune, pray or give offerings to said entity are also open for you to interpret. 

I'm glad we've managed to wrangle up this amount of interest; one or two more players will give us plenty to work with. Expect an OOC later tonight or tomorrow - most of the worldbuilding is done mid-RP, with player input, so don't expect too detailed a world just yet! The details are going to be ironed out as we play. :sun