Hi, look at removing apps that you no longer use. Or you could look at removing some media that you might have on your phone, like pictures, music, movies etc. Have you considered buying an SD card for the phone?
Most apps can not be moved to the sd card. You can move all videos, pictures and music to the sd card. Remove un needed apps and clear cache. Search for "memory" on this forum to find a lot of information on memory management!