DO NOT fly for free!
Profesional Pilots, means you are get paid, not that you are trying to sustain a hobby.
I think the best way is to go to the Tuna boats, CFI, of better, go to operators who need copilots.
I got my first job as a copilot in Bell 212's doing offshore and powerline patrol with only 37.5 R22 hours and a fixed wing CPL (never flown in a piston since) and I didn't get it by looking into the internet or reading magazines, I got it by going to the airport everyday, meeting people, making lots of phone calls, being persistent, and being willing to move to where the opportunities are, if you live in a place where to be a helicopter pilot you need to work for free or almost, then you are maybe in the wrong place, or you selected the wrong profession for the time being.
Mis 2 centavos