This guideline features the best practices I have established during my development career. This is all just personal preferences but may be a good way to start if you are new to RPG development.
All in all you should not have to code too differently than in any other programming language. Some will argue that my code looks very much like Java or C# because I like to use procedures, like to keep my procedures short and use meaningful names for variables and procedures. But this is something you should do in every programming language.
Use your mind!