Getting started as a solo dev

Hi guys,

I’m semi-new to programming. I’ve taken a lot of online code classes over the past several years, and feel comfortable with being able to google my way to stack overflow to solve problems. I’ve also learned about UX/UI design, and object oriented design, and I’m looking to get started with my first project intended for public release. I want to make sure I’m going about this the right way, and that I’m not going to screw myself over later, but I’ve found very little information on the operational aspects of solo development. I’ve never worked on a development team before, so I don’t really have any experience to base off of (like, what tools should I look to for organization, beyond a repo to store code. Do things like Agile still work when my team consists of past me, present me, and future me, or are there other approaches?). In general, any advise for someone inexperienced setting out on a larger project?

EDIT: This is also a project from my own imagination, so there are no customer specs to build from. Should I start with building specs based on my UX research?