My strategy with my Holga is simply to let the camera adjust the exposure automatically. :rolleyes:
Seriously, exposure accuracy is not high on my list with this camera. I just leave the camera set for cloudy, put 400 speed C-41 film in, develop normally, and then use my enlarger to adjust.
Sure, I have had some thick negatives, but they have all been very workable with plenty of highlight detail, even from full sun shots in Death Valley on the salt flats.
I guess my advice would be a switch to C-41.