The three most important things are: simplicity, simplicity and simplicity. Things that are more simple have less ways they can break, and if they do they're easier to reason about.
Be constantly asking yourself: is this the simplest way to do this? Is there a simpler way? e.g. Do you need a database? Do you need a server at all? How far can you get without these things? On the other hand maybe you're looking at newer serverless architectures? Is it really simpler to do that than use a VPS?
Be constantly explaining to yourself why the way you're doing it is the simplest and most robust way.