I think the most important step is to get it out there. So:

1. Choose a license. These resources might help:

• https://fontsarena.com/licenses-explained/
• https://choosealicense.com/
• https://opensource.org/licenses

I'd stick with the licenses made for fonts or in use by other font projects, as there are some specifics to fonts licensing.

2. Choose a name

3. Sign up and create a repo. Upload your project.

That is the "get it out there" step. If you want to be open, generally speaking you want to include a LICENSE file, your creation in the format you're editing it and other people can load and edit it, too. And the exported file in case of something like this, so people can directly use it without learning how to convert a font into a format that is usable. It's also good practice to include a README.md with explanations and a summary of what this is.

I think that's a sound approach for open source. And it's generally alright to learn as you go. Even if you don't get everything perfect at once, the most important thing is that it's available. People might pick up on it. And they will file bug reports and issues if they like it some other way. So you'll be directed into the right direction anyways. And once you have something to show off, you can start talking about it or make people aware of its existence.

(And maybe skip all the boilerplate and complicated extra stuff at first. You don't need an AUTHORS file, no code of conduct, no documentation if there isn't anything complicated to explain... Just stick to the important stuff and don't make it unnecessarily complicated and distracting for your users.)