Hi,
I first went to the tutorials section, where I first read the different output strategies. After reading the three different main strategies, I decided to go with my first steps using the Delayed Output strategy.
https://processwire.com/docs/tutorials/default-site-profile/
https://processwire.com/download/site-profiles/
Choosen: Default profile (standard/intermediate edition)
Then I started to add some pages and started to add simple things in the template files using the great Processwire API and some plain PHP. After I created my first prototype and got the go from my customer, I reimplemented the site with some more structure using PageClasses and Latte template engine for the views, while sticking to the delayed output strategy. Some times later I added Markup regions to my sites frontend login template to alter the header and footer region for guest users.
My advice is to start simple using the Default profile (standard/intermediate edition) and work on some tutorials and try to alter or add functionality in small steps.
Cheers