Final answer:
Mark Twain held jobs as a printer's apprentice, Mississippi riverboat pilot, and journalist/editor before becoming a famous writer.
Step-by-step explanation:
Mark Twain, the pen name of Samuel Langhorne Clemens, besides being an acclaimed writer, held several other jobs. Before rising to fame as an author, he worked as a printer's apprentice, and later on, he earned his livelihood as a Mississippi riverboat pilot.
Additionally, during his time in the West, Twain worked as a journalist and served as an editor for the Virginia City Daily Territorial Enterprise. His experiences in these roles notably influenced his works, providing him with rich material for his stories and characters.