The usual technique over here is to get as close to the edge as possible, with the rotor over the water, and the toes of the skids just barely inside the edge of the deck. The rationale for this is that the wind hits the wall below and is deflected up and into the rotor, providing some additional lift. The wind usually goes up, and then on the downwind side of the heliport is actually blowing down, much reducing lift, so the best place to be is as close to the edge as possible. All this is assuming a standard production platform heliport, but the same effect is usually felt coming off a drilling rig. The technique used when at 11,899 lb, little or no wind, and very hot, is to get to the edge, and move nothing. It's important to be very smooth, and to move neither the cyclic, the collective, nor the pedals unless absolutely necessary, and then as little as possible. Stirring things around destroys lift. We hover there at 100% torque, and eventually some lift comes along, which can be felt as the helicopter starts to rise. As this happens, smoothly lower the nose to move off the deck, and do nothing quickly, or else the deck may rise up and strike the tail. If 100% torque provides enough power, then the takeoff is made in one continuous movement. You usually know before the skids break contact whether there is enough power to go immediately, but it's still a good idea to do things slowly.
Some may be horrified at the technique, but it works, as evidenced by tens of thousands of takeoffs annually, without a single accident that I'm aware of during the past 20 years. The exposure time is minimal, a couple of seconds at most, and everyone involved has accepted the risk.