Gathering of data, and research
Consider this your homework. You want to understand your game, creative direction, art direction, and target market. You want to collaborate with all disciplines and to achieve clear communication with your art, code, and design teams. You also want to ensure that everyone is on board and aligned with your vision of the game.
Ask questions. What’s best for the user? Why are we doing this? Is this the best way to do it? What are the theme, tone, and style? In what era is the game being set?
All these considerations will find their way into your UI.
Lastly but not least, always think about usability.
Treasure hunting – references
In addition to doing research and gathering data, use the design stage to find the best and most relevant references from movies, games, television, mobile media, magazines, and posters. Use these references for inspiration, education, and help with forming your design decisions.
Be aware of the design trends. This will help you avoid designing a piece of work that is outdated because it is based on a trend from the past. You want your design to outlast the console generation or a hip trend that lasts about a year. Always challenge the status quo and keep the brand and the big picture at the forefront. Even within a franchise, each game should look and feel unique.