Depending on the operating system of your phone (I assume iOS or Android) you have a few options in general. First off, set a data limit on your phone so you will be warned when you are near to the end of your data cap. Next, if your phone supports it, turn on Data Saver. It might be called something else, depending on your device and OS. It basically tries to compress most of the data when you browse the Internet. It may lower the quality of some content. Check your browser to see if you can add an extension to block intrusive ads too. Don't block all ads though, as it's someone's bread and butter. But getting rid of intrusive ones gives you a more enjoyable experience and saves some data. Another great way to save data is turn of the Auto-syncing of certain accounts like e-mail and social media, and sync them manually when you're on WiFi. Lastly, try not to watch many videos, especially in high quality, and make sure that you're apps don't update over your mobile connection. Hope this helps. If you can name your device, I might be able to help further.