Similar to other projects planning is key to finding an equalibrium between fun/tacital gameplay and the best use of space. Use a white board or a paper pad to plan out multiple iterations of the level you would like to build. Make sure to understand what demographic and focus of the game you are creating the level for.
○ Symmetry can be used as a trick to easily balance play areas, typically multiplayer combat-focused games will commonly follow this.
○ Focus on the theme and style of the game that you are building the level for, the focus of your game has a major impact on how players will interact within the play area.
Begin greyboxing your level using only basic cubes to gain a better understanding of how players will traverse the playspace. Physical aesthetics can be tweaked/edited in later on.
It's almost impossible to understand how your level actually plays without rigorous testing. Playtest the map after every major iteration, making sure to move throughout every area that you intend on players passing through.
Depending on the engine used you may be able to test different spawning locations. (In the Unreal engine try right-clicking on an area). This can be used to quickly test areas that may cause nav-mesh or pathing issues.