Information and Updates

I have been asked to prepare technical content for a US project, and I am finding the writing side harder than the research. The information is already there, but turning it into simple, readable sections is taking ages. I came across Technical Writing service in USA while searching for possible help. Has anyone worked with a technical writer on a similar project? How involved were you during the writing? I would appreciate hearing about the process, especially how you made sure the writer understood your subject correctly.