Handguards helps a lot...but ride in temps down to 0deg (fahrenheit) so made these from some 4 litre plastic cans had laying around. Looks like shit but helps a lot reducing wind chill and took 15 minutes. Rigid enough to take wind pressure but soft enough to yield in a crash.
Tried hippo hands and they've even better but don't like the feeling of trapped hands. Heated grips and heated gloves also helps but reducing wind chill is most important if any speed.