There is not ‘ the ‘ way, but…
I would advise you to download and install XAMP so that you have a local test environment.PHP alone does not have that much to do. A good web application built with PHP also uses SQL databases to store information in a relational database.
Notepad + + is an editor for writing code, but there are sat other editors.The important thing is that there is color coding and line numbering in the editor, because that helps you detect bugs and you will undoubtedly create bugs or logical errors. However, you can even be sufficient with Notepad, but then you make yourself difficult, as this does not have color coding and line numbering.
An IDE like PhpStorm or Visual Studio Code is advisable when your Web application starts to get bigger, because these IDE have good search features that will quickly help you to track down and customize bits of Code.
It is advised not to write the PHP code completely procedurally, but also Object Oriented, because it helps you to reuse pieces of code easier.
What also helps is to make a separation between controlling and steering code, executing code and code that display things and separating the HTML structure as much as possible from the PHP code.
If you want to load pages quickly or reload parts, it is also advisable to use AJAX.
For the speed of large databases with a lot of information it is important to think well in advance about the structure of the tables in the database and what you use as indexes.
For security It is good to use a recent version of PHP with MySQLi prepared statements of PDO.This to prevent SQL injection. Of all external variables it is wise to filter them.
For loading information that does not necessarily have to be relational, it is also useful to look at XML.XML is also very useful when exchanging information with other platforms and Web applications written in other languages.
For Exchange to other Web applications it is also good to look at JSON.
If the Web application has a lot of file uploads in it, it is important to think about the folder structure and how you track changes, it can be your salvation in the backup of such files.
If there are daily actions that need to be performed by a PHP script it is wise to think about setting up a Crontask.
Eventually the Web application will also need to be hosted, so a good web host is also important to have.
All in all, there is a lot to do if you want to do it right and in ‘ the ‘ way you think of everything.The practice is, however, unruly and I too will probably have forgotten what to report here.