As has been pointed out several times, the original post was about "what to do if...." There has been lots of good advice posted in response and all of it relevant.
I am concerned, however, at the level of acceptance that "inadvertant IMC" is just something that we as pilots have to deal with. We even have an experienced instructor admitting to inadvertant entry twice - but it was his student's fault!!! I cannot think of any circumstances in a helicopter, GA, by day, that mitigate an inadvertant entry into IMC.
IMHO it should be renamed "Negligent Flying" and investigated in the same way as, eg. inadvertant entry into controlled airspace.
Maybe I am missing something, and if so, I would be very keen to hear of any circumstances in GA helicopter ops where "inadvertant IMC" should not be renamed "negligent flying."