Jobs as we know them today were extremely different

There are two texts I would recommend reading for an explanation of this. The first is Life in A Medieval City by Joseph and Frances Gies (published by Harper Perennial) goes into this specifically. The book is an in-depth study of the city of Troyes, France, during the High Middle Ages, but focusing around the middle of the 13th century.

The second is The Medieval City (Greenwood Guides to Historic Events of the Medieval World) by Norman Pounds. These two text books together give a great comprehensive explanation for how people got jobs back during the Middle Ages.

Before I summarize their explanations, I do want to remind people that jobs as we know them today were very different 800 plus years ago. Most scholars agree that in most of Europe, 90% or more of a regions populous lived in agricultural centers rather than in urban environments. Living in cities provided a significant threat to the average burgher and it was worse for anyone who lived in poverty. As a result, many people avoided living in cities because of these heightened risks.

Specifically, if someone wanted to find an occupation, it generally would not be up to that person. Page 48, Life in a Medieval City)explicitly explains the process. Parents of a boy, possibly a pre-teen generally, would seek out a Guild or go directly to an Artisan and request that their child be trained. A guild would then draft up a contract -- these contracts were extremely valuable because it protected the apprentice and guaranteed him certain rights, such as being fed, given proper clothes, and protected him from being physically harmed by a member of the artisan's household (particularly against the wives who were known for berating apprentices.)

Once the contract was accepted and the mutual terms agreed upon (an example could be 7 year contract, with the first six of them unpaid) it would be ratified by the guild. Once the time period elapsed, the apprentice would have a few options. The first is they could petition the master to allow them to stay on, but this was rare because now the guilds would require them to pay the apprentice more money. The other option was for the apprentice to request a 'craft test' from the guild, and request that they be allowed to open their own shop. Many cities, like Florence, had a cap on how many of each particular shop they could have in the city, so the apprentice could consider traveling to another town or city if the cap in their present town was full. The apprentice would not have to worry about having his own family since many guild contracts prevented the apprentice from marrying since he would live inside his master's home. (Chapter 6, The Small Business, Life In A Medieval City)

Hope this helped a bit

My guess is that it's not exactly typical, but you might enjoy reading this CV written by Leonardo da Vinci.