Clear some space with PhoneExpander
1 Trash temp files
Click on Clear Temporary Items. PhoneExpander will build a list of caches on your device that can be removed. To get rid of them all, click the Clear button (which will denote the space saving). To be more selective, use the checkboxes before clearing the caches. Once you’re done, a sheet will advise regarding how much was cleared, enabling you to continue (Delete More) or return to the main window (Finish).
2 Remove weighty apps
Click Remove Apps. Again, the app will create a list of relevant items on your device. Apps are initially listed from largest to smallest. As with the temporary files, the process for removal is simple: select one or more items then click the Remove button. Note that in removing apps from your device, you will also remove all associated data and settings at the same time (unless the app stores such things in iCloud).
3 Delete old videos
Click Clear Photos. The interface here is different from the others, in that it gives you a slider to determine the age of what you want to remove. Drag the slider left to include older (and therefore, likely, fewer) files. Use the checkboxes to select whether to remove videos and/or photos, then use the menu to determine where the backups of removed files go. Click ‘Backup & Remove…’ to complete the process.