By simply driving:
when you drive with waze on, you cellphone sends us GPS trace points. These help validate the location of the roads, help fix map problems, ascertain driving directions and whether options like left-hand turns are available, and so on. But that's not all, your driving speed helps us determine and share with other wazers whether there's traffic or not, and how heavy it is. When you Just Drive the map gets better for all of us and you get the benefit of a live map, updated by other wazers.

By actively reporting directly from the scene:
if you see a roadside hazard, speed trap, an accident, traffic jams, map errors, or if you've just freed up a parking spot - notify the community. With a simple, 3 click wizard you can report live to everyone on waze. You can add pictures to your reports, and even automatically tweet them to your followers.

By recording roads that don't appear on the map:
That's a fun one. if you are driving a road that doesn't appear on the map, you can record it (from the report > map issues menu) , and it will be added to the map, and soon after will be available to all other wazers (usually the next day).

By editing the map itself (on www.waze.com):
Those of you with a passion for map building and editing can contribute enormously and take a huge role in the building by editing the segments you've driven, or even assuming responsibilities for entire regions.