[i_am_proteus]

Have an extremely specific vision for what you want to do after getting the degree.

The lion's share of general "entry-level" opportunities for newly-minted technical masters/doctorates will struggle to value whatever experience you had before going to graduate school. This is less true for certain industry-specific positions, which is why identifying those positions before starting is a good idea.

If you're comfortable restarting your career as a junior researcher in your late 40s, be aware of the unusual place you'll occupy in the academic hierarchy.