treebear, rip the sleeves off old t-shirts, they make excellent headbands.
The material is thin enough so it does not add too much heat to your head.
but thick enough to absorb sweat, this works for me.
The problem I have with safety glasses is they are useless in the rain, the glasses get wet, the saw shavings and tree dirt then stick to the front of the glasses so they can make the job more dangerous through poor visibility.
So keep your visor. As you will know the saw shavings just hit the visor and bounce off.
Glasses are important, but remember to keep your visor down when you are chipping.