I keep meaning to write a blog post...

The short answer, start with a package management system like conan or npm (we rolled our own - releasing 1.0 the same month I first heard of conan which was then around version 0.6 - don't follow our example). Then you just need processes to ensure that everyone constantly has the latest version of all the repos they depend on - which ends up being a full time job for someone to manage.

Don't write your own package manager - if you use a common one that means your IDE will know how to work with it - our custom package manager has some nice features but we have to maintain our own IDE plugin so it can figure out the builds.