Opaque is fine-ish but if you're over forty and not really that trendy then steer bloody clear. Reminds me of my mum in socks and Scholls.
Long skirt/trousers- open toes (pedicured toes only) good
Open toe tights with open toe shoes no.
Tights with open toe shoes no.
Opaque tights with a seam across and open toed shoes - definately no.
It's winter. Why not boots? Ankle boots with thick tights and skirt ok.
Need to know the rest of the outfit really!