My Droid Turbo has used almost all of 2gb in the first month of mobile data. I am on WiFi 95% of the time and all I use mobile data for is google maps.
Anyone else see that the Droid Turbo is calculating WiFi data a mobile data?
Best practice is to disable mobile data when not in use. Also, instead of Google Maps which uses a lot of data depending on if you have map tiles cached and satellite/traffic view off you could use HERE maps which is free and also does not use data in its offline navigation option.
You can also disable some of the more obscure apps that you do not use. Big Data users are My Verizon, Verizon Cloud (use Google instead). There are quite a few and a list can be obtained as to which are safe to disable or not. Then make sure your phone is set to only update over Wifi as well. A lot of data usage is due to app updates.