If you fly regularly from an airfield, see if there is a landmark - building, mast, whatever - at a known distance that you can see from the clubhouse or apron to help determine visibility.
At Fairoaks, you can see a large rectangular office block in Woking that's about 4 Km away.
If I can't see it, the viz is c**p - I might as well go home! If I can see it but can't make out the windows, the viz is marginal, and I won't bother going out of the circuit if I fly at all - VFR only, me! If I can see the windows on it clearly, the viz is good enough - at least locally.
Obviously, this is in conjunction with TAFs, METARS, 214 and 215 forms. It's just a quick check that works for me.
SD