There are multiple approach to world building, such as a top-down and bottom-up. All are valid and have their merits and undesirable consequences, which can be mitigated.
Top Down
The top down approach can be described as starting with the big picture and working our way down to smaller elements. For example, when it comes to physically designing the world, we decide how many continents it has and where they are in relation to each other. Next we focus on a single continent, deciding what nations exist and what forest, mountains, and other features exist and where, possibly drawing a map. We would repeat this on other continents. From there, we would choose a nation and decide on where its major cities and towns are and work out their relationships before moving on to other nations.
Regarding life, we would start with creating gods, the reason being that these deities presumably have attributes that affect the species, plants, and animals they created. All of those should be influenced by the land features we’ve already created. And they should have relationships with each other. The species might have in turn caused supernatural disasters that left residue behind and now everyone avoids that place.
The advantage to such an approach is cohesion. The impression of randomly created pieces slapped together is less likely, as are world building holes (like plot holes). The latter would include something like a river that has no mountain source, but we can’t add one because we’ve already decided that none of the nations near it have a mountain range and their cultures are somehow dependent on that, for example. And maybe we can’t get rid of the river, either.
The disadvantage is that world building can feel like a big homework assignment. We’re doing this in a specific order and may not have ideas when we need one to continue. Getting stuck can ruin momentum and enthusiasm. We can see a huge to-do list and feel overwhelmed. The process of creation is supposed to be fun; creating things in a freewheeling manner helps with that and also causes interesting ideas to develop.
