Here are some examples:
* Artist: A practitioner of art.
* Scientist: A practitioner of science.
* Politician: A practitioner of politics.
* Dentist: A practitioner of dentistry.
* Pianist: A practitioner of piano playing.
There are other suffixes that can also indicate a practitioner, but they are less common and often specific to a particular field:
* -ian: (e.g., physician, librarian)
* -er: (e.g., teacher, writer)
* -or: (e.g., actor, operator)
The best suffix to use will depend on the specific field or profession.