This is an invoicing system I made in 2006 when I started my computer repair/programming business UziTech. I still use this for the few clients that I still have because it works pretty well. This was about a year of adding features and tweaking design.
- Code Style: use a linter.
- Code Separation: break code into smaller files for easier readability and testing.
- Testing: Testing code makes it easier to update without worrying about breaking something.
- IDE: use an IDE. This was all written in notepad.