How to manage the storage

Apple support's article *links below) have some tips that may help:

It's a good idea to back up everything on your iPhone before deleting anything:

How to back up your iPhone, iPad, and iPod touch - Apple Support

How to use iPhone's storage "reccomendations":

If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

More info:

How to use iCloud to: Manage your photo and video storage - Apple Support

or

Delete photos on your iPhone or iPad – Apple Support

How to: Clear Other storage on your iPhone or iPad - Apple Support

All the best :-)