Ask HN: How do you plan your personal software projects?

I'm forever starting and rarely finishing personal projects. My planning is almost non-existent and I tend to code as I go along, I almost always over-engineer and never define what an MVP should be.

I'm good at Python and PHP, I'd like to learn Laravel more and I have an idea for a web app. Unlike most my ideas, I'd be more motivated to finish this one as I've wanted it as a personal tool for years and I don't like any of the competition. I'd use it daily even if no one else did.

How do you plan a project out? Do you jump straight in to code? Draw it all out on paper? If you're familiar with Laravel, do you just make it up as you go along, or do you write down all elements of the idea and plan Eloquent models etc?

Interested to hear anyone's methodologies or similar.