General
Sounds like a good gig. A couple of points:
Get an idea of the superstructure of the boat as this will dictate the turbulence you can expect. Depending on the aircraft you are flying, get the ship to steer about 20 deg off from the wind. This will give you a uniform wind over the helideck.
Don't muck around too much in the hover when over the helideck as the turbulence mentioned above will mix with your downwash and make it uncomfortable. It all depends on the design of the ship.
Have the deckhands briefed on helicopter ops. Doesn't take long but worth its weight in gold.
Lastly, however much you are pushed, don't let the boss talk you into something you are not happy to do.
Have fun.