Yes, I have worked out that I have to underexpose by exactly one half of a stop to reliably get the images I need after performing a white/grey balance. ie. Measure for f5.6 5/10 and shoot at f8. I cannot make sense of the histogram as it is all gobbledegook to me!
The histogram is not that hard once you've checked it out on the Internet. It's a good way of making sure that you are not overexposing an image by clipping the right-hand side, or under exposing an image by clipping the left-hand side.
Every time I look it up on the Internet I always come across this saying, "shoot to the right." I'm sure loads of photographers on here could explain what that means better than me, but as I am one of the few people left on the forum I suppose I ought to have a go.
In simplistic terms you ideally need the spikes on your histogram to be on the right side, but not so far right that they are right up against the corner or your image will turn out to be overexposed.
The same principle applies to the left-hand side. Only this time, if you are clipping the left side then your image will be underexposed.