Boost your creativity by studying your fictional world. Become familiar with its academics, cultures, individuals, and themes. Know these areas well so you can ground your reader with facts, keep internal consistency with rules, add diversity and conflict with opinions, and set the stage for story with possibility. It is important to know your world regardless of your genre.
Know more about your world than the best educated scholar. What history would he know and what parts of history would he not know? Why doesn’t he know this? Know the ecosystems you write in (ravens do not fly in Florida, there are no penguins at the North Pole, forests in Spring turn green from the ground up). Know the economics of the places your characters visit or live. Many people find that research prompts character, plot, and setting ideas. Even if you are not one of these people, your studies will create a more realistic and vibrant world for your reader.
Know more about the cultures than the characters who are immersed in them. Insiders tend to take their own culture for granted so be sure to have an objective view — especially if the character’s culture is similar or identical to your own! Don’t stay at the surface level but delve into deep culture. Know how this culture interacts with other cultures. Definitely know gender roles and expectations, as well as how status is decided and displayed. Remember that many individuals are from more than one culture (look at your own background) and consider clashing these cultures to create inner or outer conflict. The norms, assumptions, practices, and attitudes of cultures are a fantastic resource for inner conflict, outer conflict, and character archetypes (a possible starting point for character creation).
Know more about your characters than they (or those closest to them) know about themselves. Understand what triggers their emotions. The reasons for their motivations, as well as how and why these motives change (if you have a character arc). What is behind their weaknesses, limits, and fears. Study and develop these areas of your character — you will not only know your character better but also create a treasure-trove of barriers, obstacles, and conflicts that you can draw on for your work-in-progress when you get stuck.
The last tip for boosting your creativity is to study what you are writing until you identify your theme(s). Your theme is what the book is about. Usually it is a belief that is important to you as a person. It can be “true love takes work” or “racism is bad” or “power corrupts”. As suggested, you can have more than one theme. Once you have identified your theme, think about its unspoken facts, rules, opinions, and possibilities. Variations of your theme will appear throughout your book so studying your theme will help you express it more clearly. Studying it may also prompt scene or character ideas.
Study your fiction world when you are feeling less than creative. A world with well-developed backgrounds, cultures, and characters will also have built-in details, diversity, and conflicts. Certain themes suggest certain plots, conflicts, and scenes. A well-developed world can help you be more creative.