Ditto on the dust filter recommendation but i actually use canola oil as the lubricant instead of WD40. Never used WD40 but since it already has 1000 uses, lubricating filament could just be one more to the list.

if you don't use a dust filter, you can still add a drop of canola oil (or wd40 )on a section of filament just before it gets pulled into the extruder. Lubricating the filament can be a huge help and definately worth doing.