Use Opera Mini instead of the standard browser that came with the your phone. Most Android phones come with Chromium. What you want is to immediately install Opera Mini
If Opera Mini is not your thing, try an alternative called UC Web. This is a browser that works like Opera Mini except it looks nicer (well, in our opinion at least! )
If you insist on using Chrome or Chromium (the default browser that came with your Android) then you have to turn on Data Saver mode so that it reduces the data it uses. You can do this by opening up Chrome, going to settings and clicking on Data Saver.
You might not know it yet but there’s a browser called Yandex which has very good data saving features. Its Turbo mode compresses traffic while opening webpages to save you data and load pages quicker. You can set the Turbo mode to automatic or enable/disable it.