Creating your own theme is an option if you wish to fully covert your blog into a truly original piece of work. That being said, there’s plenty of options to help build your website beyond coding the process from the ground up.
The first path of developing a theme is exactly as mentioned: from the ground up.
You gain the full benefits of working the theme to exactly as you specify, and you also learn a wealth of information from consulting the various documentation available on the internet. The tradeoff to a from-zero construction is the painstaking length it takes to develop a theme from scratch. You’ll spend a lot of time developing the frame and any mistake made here will need to be corrected as you go.
The next option is creating a theme using a Framework as a base.
You gain the best of both worlds by saving time and gaining a basic quality of site design with a framework. These carry minimal design aesthetics and any complicated visual elements are developed by you. Frameworks are also automatically-updated, meaning a lot of the work is delegated to whoever is maintaining the framework and you would simply handle making the rest of it up to your design.
The main complication of frameworks now, is the large breadth of additional documentation that you’d need to learn about the framework itself to fully utilize it. You would need to study the HTML, CSS, and PHP files the framework provides in order to get a grasp, this is the same with every new framework you’d eventually use in the future, should the current one not be optimal.
Finally, Starter Themes are a great option to use.
Starter themes provide a similar level of flexibility to working out a theme from the ground up while also providing the base functionalities and background work that a framework provides you as well. Similarly, a starter theme is also maintained by the Theme Developer as a framework does. While there’s no major downside, like a framework you would need to study up on the files it provides in order to make the most out of the theme.
Personally, as someone who has yet to make a higher quality website theme I might look at Starter Themes to begin with. This provides me with the quality of a premade theme that I can enjoy in aesthetics while also studying how the theme works in the back-end. By looking at how the designer crafted their various theme files, I can get a grasp of that and try to work out my own themes in the future.
There’s a list of files that are required to make a WordPress theme work, some essential while others are good for cleaning the files and divvying up processes.
Index.php is the first major file, essential to allowing the theme to work. This would be your website’s main HTML file, containing all the major pieces of HTML5 and PHP code that design the building blocks of your website.
Style.css is the other major file, designing all the aesthetics of your website so that it can stand out amongst the endless sea of other blogs. This is the Cascading Style Sheets file where you can modify individual elements of a web page so that it all comes together as a cohesive website in the end.
After this, most files are divided from index.php to develop their own sides of the entire project.
Functions.php allows you to make the process of creating your theme easier by housing all the major functions and website settings. These will allow you to set up the basic features of your website and also house additional live functions that go around in your website.
Content-[TYPE].php and Content-none.php are helper files in a main file loop housed under content.php which help you with posts, calling appropriate elements to display when the requisite post (or lack of one with content-none) appear.
Header.php houses all of the header elements of the website. This is your top banner and navigation set of code for making the first impressions count.
Footer.php is a block for the very bottom of your website. Within you can set simple actions like a watermark or copyright to let people know who owns the website. You can also set widgets here to provide additional functionality.
Sidebar.php carries all of the various widgets you could need. By widgetizing your blog, you provide additional functionality and other fancy features that can enhance a viewer’s experience with the blog.