Since my family is largely made up of Voodoo practitioners. I am familiar with the practice.
Concerning Voodoo worship services, a Voodoo clergy is responsible for overseeing all ritual services. They have the responsibility to mediate between the spirit world and the community as a whole. Priests are called houngans and priestesses are referred to as mambos. Assistants are called hounsis.
A typical Haitian Voodoo service can take place in either a temple or a private home, though it is a true community affair. It can take days to prepare (cooking special foods for a pre-ceremonial feast, setting up altars, and so forth). The actual ceremony includes animal sacrifices (e.g. chickens, goats, dogs, cats), Catholic prayers, Indigenous African prayers, singing, drumming, and rituals that include naming and greeting different spirits by the family.
The most common practice in Voodoo worship service is possession by one of the Lwa or spirits. These lesser divinities are not truly gods, but the spirit of a great ancestor, male and female. Worshipers summon and entice them to control their physical bodies and voices to speak to others — giving readings (using tarot cards, Ouija boards, and other mediums) and spiritual advice to all who approach. Unlike in a Christian or UU church, Voodoo worship services tend to be extremely energetic, ecstatic, and exhausting, as they usually last for hours.
On a personal level, devotees of Vodou erect and maintain small altars in their homes. These typically include statues of saints, photos of ancestors, candles, and various gifts favoured by certain Lwa. Individuals in the home on certain days, light candles and say certain prayers (often African prayers).