By far the biggest time saver is to use a language with a strict static type system (ideally Kotlin for JVM, F# for .NET, TypeScript for Node, etc.)

Practice TDD, even on small projects, and write unit tests as you go

Learn how to use an IDE-integrated debugger properly

Avoid magic at all costs (the reflection-based DI in .NET is a particularly egregious example of this -- it is literally undebuggable)