It is assumed that, as a serious FileMaker developer, you are using FileMaker Pro Advanced with access to custom functions and other advanced features. Taking full advantage of FileMaker requires this investment.
- www.ibm.com PHP OO Article This is a good read about PHP OO Good habits
- Encapsulate your code — having to change things in many places is a pain
- Write highly cohesive code by using strongly named grouping patterns - reuse is the goal
- Make it DRY — If you see it appear a second time then make it so it will only have to be changed in one place (Don't Repeat Yourself)
- Avoid tight coupling — i.e. write code with fewer dependencies
- Handle all possible errors
If you currently have messy code and want a head start on code cleanup you can use this tool FileMaker Calculation Formatter. While it does not adhere to the standards outlined here. It does a lot of the hard word for you.