I totally wipe the glass to be free of any oil or foreign material that might cause uneven heating of the glass bulb. Next would be any water intrusion into the socket or around the bulb. Next would be good tight connections, maybe a dielectric grease on the socket in case there is a little corrosion in there.
Just some thoughts,
Bob Weis
I run a Summit harness on mine, no problems, and it unloads some of the current going through the headlight switch.