The commonly used methods are IRV or STV, where a preferential vote is made.

IRV is often used where you will have a single winner, and STV for multiple winners.

Other frequently used methods are described below.

Approval Voting #

With approval voting, a voter can approve of as many candidates as
he or she likes, and the candidate approved of by the greatest number
of voters is elected. A voter approves of a candidate by listing the
candidate on the ballot, and the order of the candidates on the ballot
makes no difference.

Random Transfer STV #

Random transfer STV (RTSTV) is a method that treats each vote as a
single unit that votes cannot be split up among multiple candidates.
Because the order of the votes can change the outcome of the election,
it is called a “random” transfer method.

Instant Runoff Voting #

Instant runoff voting (IRV) is more commonly used to elect one
candidate but can also be used to provide semi-proportional representation.
Ballots are first distributed according to their first choices. The
candidate with the fewest number of ballots is eliminated and the
ballots are transferred to their next choices. This process is
repeated until the winners are determined.

Single non transferable Vote #

With the single non-transferable vote, only the first choices are
used in counting the ballots, and the candidate with the greatest
number of first choices is the winner. When there is only one seat to
be filled, this corresponds to a traditional plurality election. When
there is more than one seat to be filled, this provides a simple form
of proportional representation. You should make use of the voter restrictions (min and max options) for this type of count.

Scottish STV #

Scotland enacted these rules for local elections in 2007. This is a
straightforward implementation of STV and recommended to
organizations using STV for the first time.