I'm curious to see what others post as I will be grinding with a Lido3 shortly.
My answer would be: what ever works for you...
I'm currently doing french press with a pharos with a medium-ish grind. I seem to prefer 12.5g of coffee to about 400ml/g of water. Most here would probably find that watery/weak, but I like the flavour I get. I tend to switch coffees a lot between Ethiopian Yirgacheffe, Sumatra Mandheling, Thailand Doi Chaang and various South Americans. All except the Sumatra (dark) are a medium roast.
I find I get a good enough brew to distinguish easily between the different coffees and taste most of the notes associated with a particular roast. I guess I just like my coffee weak.
For grind, I settled out at a level where my french press catches all the fines (the pharos creates more fines than the lido).
I'm probably not as particular as most here though.