Anything thats not asphalt or concrete, be cautious on it. You never know how much traction you need until you run out......so play it safe if its wet, leaf covered, anything else thats unfavorable.......slowing down and taking your time only costs you THAT time instead of parts, paintwork, medical, etc. I use a simple spray on detailer for my visor. Water does collect on it when its raining or foggy, but just keep your eyes on the road while you slowly turn your head left and right to allow the wind to blow the water off each side. You're doing it right by riding cautiously when you're unsure of the surface conditions, but you're doing it wrong when riding with your visor up. Try some anti-fog on the inside and maybe RainX or detailer on the outside of it to help shear beading water