Choppersquad
I'am afraid there is no simple answer, as many of us I've been there several times, and several of the suggested approaches were used depending of the circumstances. But one thing is for shure, unless you are trained for it STAY OUT.
It all depends on your skill and the circumstances, but one thing is for shure, you don't want to be in there unprepared : not only heli-attitude wise, but the whole situational awareness. Even manipulating a GPS in IMC/Single pilot is very very difficult, especially in a light heli.
At 800' I would first try to descend. Normally you will not enter cloud just with one bang, but just see it very late, so look back away from it to find a last visible spot and lock on to that, so probably meaning some turning back and landing, but still essentailly in VMC.
In mountainous area's you probably will want to climb out, but you will need to know the height of the cloud and the mountains.
Once in the cloud you will have no time to do some botlang reading.... Flying over the cloud requires prior meteo knowledge, you don't want to get stuck at 5000' in the cloud or with a solid deck below you, unless you are IFR rated. Even when trained, without auto-pilot it is very demanding to fly, so you will spend incredible mental energy and last not very long.
The last years two full IFR Agusta 109E's crashed of people I know, in the fog with high time CPL's at the commands, that should make it clear that you don't want to be there. Set your personal attitude to avoidance.
Delta3