Welcome to Android Forums! I'll try and help as best I can.
While I don't have the same model phone as you, I have dealt with low storage on other phones in the past. If you go into your phone settings, and then to apps, application manager, or whatever your phone calls it, you should be able to see a list of all apps on the phone. You should be able to sort that list by size. You can then determine which things are the biggest offenders. You can safely clear the cache of any application, but that is only a temporary fix. Clearing the data is not recommended unless you know for sure you don't need it.
In my case, the biggest offender was the app "Dialer Storage." It took some time, but I finally found out that "Dialer Storage" is used to store your text messages. If you get or receive a lot of pictures via MMS, this can get huge quickly. I went through all my MMS, saved the pictures to my SD card, and deleted the messages. This freed up lots of space.
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