As J.R.R. Tolkien, the process of creating a world, or "subcreation" as I like to call it, would involve several key elements. Here are some steps I would follow:
Establish a foundation: Begin with a general idea of the world you want to create, its history, geography, and culture. A strong foundation will help guide the development of the finer details.
Mythology and history: Create a rich and compelling mythology that underpins the world. This can include creation myths, stories of gods and heroes, and historical events that have shaped the societies and cultures in your world.
Language: As a philologist and linguist, I believe language is an essential part of worldbuilding. Develop languages for the various cultures in your world, paying attention to phonetics, grammar, and vocabulary. This helps to create a sense of depth and realism.
Geography: Design the physical landscape of the world, including mountains, forests, rivers, and seas. This will affect how societies develop and interact with one another, as well as the flora and fauna that inhabit the various regions.
Races and cultures: Populate your world with diverse races and cultures, each with their own unique customs, beliefs, and societal structures. Consider how these different groups interact with one another and how their histories have shaped their relationships.
Politics and economy: Develop political systems, power structures, and economic systems that govern the societies within your world. Consider how different factions vie for power and the implications of their actions.
Characters and stories: Craft compelling characters who inhabit your world and give them personal histories, motivations, and desires. Their stories can help to showcase the intricacies of the world you've built and make it feel more alive.
Themes and motifs: Weave themes and motifs throughout your world, such as the struggle between good and evil, the power of friendship, or the consequences of power and ambition.
Remember, worldbuilding is an iterative process, and it's essential to allow your world to grow and evolve as you develop it. Be open to change and embrace the journey of discovery.