design – How do I start the transition to OOP in php?

I've been writing php for more than a year, but mostly just the procedural style.

For now, I would like to implement a new type of user "company" on my website and I thought it would be a good idea to start implementing some OOP patterns to start doing it. For example, this company can create activities on my website and add multiple addresses. I am having a hard time knowing when to decompose what in a design pattern. Can anyone give me some advice on how to see where to start working towards a certain pattern?
And what are some of the interfaces / classes / abstract classes most used / ??? Used in a typical raw application for different types of users