Checking your data usage on your device is convenient, but the function is limited, and you should rely on it only in a pinch. It's better to track data through a carrier-specific app, such as AT&T's MyAT&T app or Verizon Wireless's My Verizon Mobile app. The main benefit of using one of these apps is that you'll have an accurate estimate of how much data your carrier believes you've used, and therefore how much your carrier will charge you for.
If you want more data and tracking options than either your device or your carrier can provide, consider using a third-party app such as Onavo Extend to track your data in a more detailed manner. Onavo Extend, which is available on both Android and iOS, is a free app that offers detailed monthly usage reports and data plan analysis, information that can help you determine whether you're using all of the data that you're paying for each month. Onavo Extend also "extends" your data plan by compressing your incoming and outgoing data so that you use less data overall.
Wi-Fi: It's everywhere!
The easiest way to reduce data usage is to take advantage of Wi-Fi hotspots, which are basically everywhere. But finding a fast, reliable Wi-Fi hotspot is tough, especially if you're depending on your Android or iOS device's settings menu. Tapping each Wi-Fi hotspot and hoping that your phone will be able to connect—and that you won't bump into a password prompt—is pretty tedious.
Instead, use a free Wi-Fi finding app, such as JiWire's Wi-Fi Finder. Available for both Android and iOS, Wi-Fi Finder contains a database of over 550,000 Wi-Fi hotspots in 144 countries. You can use the app's regularly updated hotspots map in conjunction with your phone's GPS function to find the best Wi-Fi in your area, or you can download JiWire's database so that you can still peruse its map of Wi-Fi hotspots even if you're currently offline. For every hotspot, Wi-Fi Finder lists details that you can't get from your phone's settings menu, such as the provider (AT&T, Comcast, or the like), the type of location (hotel, café, and so on), and whether it's a free or paid hotspot.
If you're concerned about apps potentially leaching data from your mobile data plan—for example, if the Wi-Fi connection is sketchy and your phone slips back into mobile-data mode—switch your device to Airplane Mode, which will automatically turn all data, including Bluetooth and Wi-Fi settings, off. Then, switch the phone's Wi-Fi feature back on to use the Wi-Fi hotspot. This tactic is especially helpful if you're using your device in another country and you don't want to get hit with data roaming charges.
Sign up for CIO Asia eNewsletters.