This is an interesting article I was reading awhile back from USA Today. It explains how a virus on a smartphone can cause data usage and effect the battery, I'm certainly not meaning the phone has a virus, but worth reading.
Do you have all of the bloatware that you do not use disabled? Do you use Facebook, Verizon Cloud or something else that typically uses a lot of data?
1) Disable any bloatware app you do not use
2) Change all of your contacts to google then disable Verizon Cloud and or Backup Assistant
3) change your Play Store settings to only auto download with a Wi-Fi connection
Go into your device's settings and click on Data usage to see which app is consuming the data. Then go into that app's settings to see if there is a wi-fi only setting. It might be set to use the network instead of wifi.