This is a copy-and-paste of my current thoughts on the process of writing IF. I’m not an expert in this, but I put this out there for what it’s worth.
It’s kind-of a data dump, which is not the best online form; I’ll divide it by topic when I have a bit of time.
There are plenty of people who have better insight than I do in writing superlative IF; but this is the first attempt I’m aware of to define, fairly rigorously, the general case, and to give due attention to every part of the general case. So, for example, I discuss gates in some detail, which isn’t something I’ve seen discussed elsewhere.
It’s written as a ‘formula’ with the standard understanding, that IF authors should write the kinds of games they want. This is a manual on how to fly a plane: it doesn’t tell you where to go or what maneuvers to execute.