Well Begun is Half done. That is pretty much true.

Ideation

• I get the idea. Maybe from a sleepless night
• Maybe from a [[Not Invented Here]] situation

Research

• I search about the idea I have. If there are any blog posts/write ups where I can bootstrap from.
• I search GitHub for any implementations available / code samples

I'll do it Phase

• Imagine how I'd want the final result
• Iterate on implementations. Which Language and which framework.
• Ease of Writing.
• Start to Write code till it gets in shape
• Write more code to prettify it
• Show off for my current progress
• Get FeedBack
• Write comments(Very very important) in code/annotate code
• Repeat 2 for any new features
• Blog on it.

TL;DR: There isn't a golden rule to kick something off. I picture how it'll be finally and work on that.