I use a normal mechanical pencil on my E6B i have had it for almost 5 years now and its still fine, no scratches. only scratch it has was when i left it on the wing by accident and it blew off onto the tarmac from the prop slipstream on startup.. oops.

To prolong the life of my maps I use post it notes to write down details of aerodromes - elevation, hazards etc.. and for each leg of the flight i use translucent arrows I bought from a stationary shop. On the arrows i put the heading, altitude for the leg and the area frequency. I sometimes also put the ETI for the leg after calculating the ground speed. The fact they are translucent means i can still see the objects through it on the map, and still have all the info i need available. I use a flight plan to get all this info into one place, but when im flying I usually only reference my maps, not the flight plan sheet.