Where can I improve my (technical) writing products?

I love this question in part because Northeastern offers a terrific answer! The Northeastern Writing Center offers a whole bevy of resources, including some of them tailored specifically for writing in STEM fields.

They actually offer appointments, online, where a writing specialist will go over your work with you, and help suggest changes and directions for improvement. You can do this from the comfort of your pyjamas! How great is that!?

You can also use one of a number of great tools for linting your prose. One of the easiest to use is this browser app Hemingway that lints for issues and color codes them for you.