Managed services. S3 instead of building a process to store and replicate files on a file system that you manage. DynamoDB or RDS instead of managing your own DB.

Libraries instead of cutting your own code for everything.

Effective searching for projects who have already done the thing you’re about to do.

Sometimes: it’s as simple as taking a day or few days to think the problem through to ensure you really understand it.

Finding a way to deliver the needed functionality in Excel/Sheets instead of a custom application.