Unfortunately I can't give good advice as I know most of these people
after they were hired, and didn't ask them
how they were hired. I know there are companies doing that, and social networks are also very useful in it, otherwise there are companies like
http://www.safeguardworld.com/ (just one I know, not a recommendation since I never worked with it, but I know some people who did and found good remote jobs) which usually help connecting employers and employees.