In the land of 10,000 gods, the gods are very real, and common enough that even a peasant might be expected to encounter one or more during the course of their life. This means that the gods themselves have been uniquely involved in deciding where and how they are worshiped.
The gods have largely decided that they are not particularly interested in any sort of religious hierarchy, hereditary priesthood, divine lineage of rulership, or any of the vast majority of worldly power structures commonly associated with religious institutions. Throughout almost all of the land religious institutions are very small, informal affairs – simple shrines with perhaps one or two attendants (or perhaps none at all) with a single individual, considered particularly holy by the community, who leads rather informal services. Religious ceremonies themselves vary a lot from village to village, town to town, and are impromptu rather than being held at set times on a regular schedule. Various gods do have their own holy days with unique rituals and celebrations, but it is up to those who live in a particular area to organize and participate in these events.
A major exception to the above is Ten-thousand-temple City. It is here that the followers of the various gods set up extensive temple complexes, and here that religious hierarchy flourishes. Those interested in the prestige of the priesthood, or a community of of the faithful in the form of a monastic order, come to express their particular form of worship to the gods. Much of Ten-thousand-temple City is given over to vast and ancient religious orders, small and secretive cults, and innumerable sects attempting to gain (or cling to) power within the hierarchy. These religious organizations are continually attempting to spread their influence beyond Ten-thousand-temple City, but are frustrated by the long tradition that the area has for religious independence, and the fact that the gods themselves will sometimes step in to limit their reach and authority. The gods recognize however that some people need the structure that a religious institution provides, and so allow them to flourish largely unchecked here. The gods also recognize that it is good to have somewhere to keep records, historical accounts, and other information, and so allow the temples to continue so long as they act as repositories of knowledge and history.
The other exception is the Theocracy of One God. Here there is a single institution, the Temple of One, that acts as both the religious and civil authority over the entire nation. Priests of the One God have authority over both the temples (which are ubiquitous in every town and village) and the civil government. In fact, temples often act as the seat of the local government. Worship of the One God is strictly defined and controlled by the priesthood, with specific times, places, and ceremonies that are led and overseen by priests. Law enforcement and the judiciary are also handled by religious organizations, and religion is a strong organizing force within society.
There are numerous methods of prayer and worship that are practiced within the Land of Ten Thousand Gods. It is very common to utilize symbolic objects to represent prayers to the gods – there are so many that taking the time to pray to each one is impossible. So people have set up certain systems to streamline the process. Prayer wheels, prayer beads, prayer flags, and prayer bells are very common, and can be found almost everywhere. they come in varying sizes from small bells and beads that hang from clothing to slightly larger versions that are carried or worn, to still larger versions that decorate individual houses and local shrines, to very large versions that may decorate major pieces of art or large temples or (in the case of prayer flags) decorate entire neighborhoods.
Dwarves tend to favor prayer flags, and decorate the entrances to their underground cities extensively, while halflings prefer bells, beads, and chanting. Humans and elves aren’t particular, and use various objects at different times and places and for various religious purposes.
Again an exception is the Theocracy of the One God, which tends to frown on any sort of religious paraphernalia outside of the priesthoods. While all the objects mentioned above can be found within the worship of the One God, their use is strictly regulated and confined to members of the religious hierarchy itself. Instead of various forms of individual worship which can be done when and where a given person wishes, the Theocracy of the One God mandates that certain periods during the day be set aside for prayer. These are announced from the temples by priests, or (occasionally) by the tolling of bells at the appropriate time.