Becoming an artist in the Renaissance was much different from becoming one today. If someone wanted to become an artist in the 15th century, they had to be apprenticed to a master artist. This would last until the Master and the guild decided they were ready to be on their own. At the time, especially in Florence, Italy, almost any type of trade or profession was run by a guild. There were guilds for artists, painters, sculptors and many more.
As an apprentice, one would be basically a slave to the master artist. Each artist had a workshop. Each workshop employed numerous apprentices. These apprentices would start out having to do such menial jobs as fetching, running errands, sweeping, and maybe preparing the wood panels for painting by the master. They would then move up the ladder and be allowed to grind and mix pigments into paints. Eventually if they have shown some talent, the master artist may allow them to assist him on some of his commissions.
Many of the works done in the Renaissance and attributed to a certain artist were partially created by his workshop of apprentices. Some works of the day may not have been actually done at all by the artist given credit. This is also why most artists did work that, at least in the beginning of their career, largely resembled the artist they were apprenticed to. Any work they did as an apprentice had to look like the artists own work, and be indistinguishable from it.
In the Renaissance, artists did not create whatever inspired them. They had patrons, or backers, who funded their works, and in so doing, decided what was painted. Religious works were the predominant type of painting commissioned. Most of the wealthy patrons also had their own chapels on their property, and would commission altarpieces. These are usually large panel works that were placed on the front of the altar. These wealthy patrons wanted to be recognized for their good works in having these religious works made, and invariable had a likeness of themselves set into the work. Many works of the time had a patron shown as a bystander in the scene depicted. Later in this period, portraits became popular. Wealthy patrons would have portraits made when they were married. There are many portraits that have survived from this period.
Most artists would move around from town to town depending on who was their patron. Most of the great masters of the time had at one point in their career the Pope as a patron. When this occurred, they would live in Rome and create whatever the Pope commissioned. As the Popes were dedicated to increasing their wealth and immortalizing themselves, most had portraits made. They also had great works created. When we think of great masters of the Renaissance, three names come to mind, Leonardo, Michelangelo, and Raphael. Each of these great men was at one time employed by the Church.
Most artists of the Renaissance were not just painters. Many were sculptors, engineers, architects, and many other things. Leonardo da Vinci had a brochure for patrons that listed thirty-six different services he offered. Artists in the Renaissance were truly masters of many crafts, and the great ones held social standing far above those of normal craftsmen.