Take a rag or even paper towel, dampen it with warm water, place it over the visor or other affected area for a minute or so. Remove the damp rag and now the dried up bug goop (that could scratch the visor if wiped while dry) is now loosened up and is a quick wipe away from clean.
This.
I don't bother with fancy products and microfiber towels.
Paper towel and a bit of water.