mkdir myproject
cd myproject
composer init
// answer questions
In case of license, figure out what suits your project best. Check licenses.
Write code. A lot depends on your use case. What do you want to build? An application? A library? Add dependencies accordingly with Composer. Have good test coverage if you want your code to be reliable.
Tag releases accordingly using your version control system. Use semantic versioning
Sort of a broad question but let's tackle at least a few issues.
In case of PHP:
Start a project using composer
In case of license, figure out what suits your project best. Check licenses.
Write code. A lot depends on your use case. What do you want to build? An application? A library? Add dependencies accordingly with Composer. Have good test coverage if you want your code to be reliable.
Tag releases accordingly using your version control system. Use semantic versioning
Publish in Github and packagist