I don't know how much experience you have, but many industries have standards devoted to their technical publications (eg. Rail/Aero/Auto/Pharma.) It would be important to indicate that you are familiar with these as well as the tools used to generate these publications (especially illustration!). In fact many of the adverts reference them specifically.

Its an ideal job at which to be self employed and perhaps even to work from home, although this will depend on the client. Two things to watch for are security and commercial limitations on removing documents from their premises which would preclude home working.

Its a job IMO that few people want to do, and if you can offer a solution to "problems" there should be work here to be found, much of it I suspect in English.

dave