The space is never enough for me as well, even when I have a 64G one. LOL. Thus, I searched every way I can to leave enough space on my iPhone. Here are methods that I found useful to solve the problem how to clear space on iPhone.
1. Delete every unnecessary app
If you find any App you hardly use, delete it without a second thought. It is as simple as that. Even the Apps you paid for can be retrieved through iCloud. Also beware of game Apps, for all game Apps could range between 500MB and IGB in capacity. Science and history Apps come with fancy 3D pictures. So make sure you check every game App on your iOS device and delete whatever you do not use. This will require tapping and holding the App icon until it starts juggling, you then tap lightly at the X icon at the corner.
2. Delete books and videos
Every 2 hour HD video or movie can occupy about 3.5 GB disk space. Go to your Video gallery, tap the edit icon on the right corner. Every video on your video App will have an X icon appear beside it. Tap the X icon to delete any video you wish to delete.
Repeat this procedure for all your iBooks. As a matter of fact, some recent eBooks come with videos and fancy graphics entrenched in them. Most reference books are mostly guilty of this. So move into the iBooks section and choose the select icon, then select any unwanted eBook by clicking on them before tapping the delete icon.
You can easily download your videos and eBooks again when you need them. All it takes is a tap of the button.
3. Set your messages on auto delete
To set up your iPhone in a way that your old messages will be auto-deleted, follow the procedure below.
Go to the settings, click on messages. Under the messages, click on keep messages and choose 30 days or 1 year. You can also set all video and audio messages to automatically expire within 2 minutes.
If you wish to delete a whole thread, simply click on messages, swipe left on the thread and tap delete. But make sure that all photos you still wish to keep have been saved before clicking on delete.
4. Delete all voicemail messages
To delete Visual Voicemails individually, open the Phone App and tap the Voicemail Button. Locate the voicemail you wish to delete before swiping left on it, and then hit the red icon to delete.
5. Clear caches from your browser
If you make use of safari most often, all data and web history may be stored on your iPhone even when you do not need them. To get the Safari browser's cache, open the settings App, tap the safari, scroll down to clear website data and history. If your browser is Chrome, open the Chrome App, hit the menu icon at the upper right hand side (3 vertical dots). Click on history, scroll down and hit the clear browsing data icon.
Here are all the ways that I have used considering how to clear space on iPhone. I know you would reach a point when you have deleted every last photo or video you don’t want, and there is still not enough space. Maybe then you should consider buy an iPad to share part of the functions of your iPhone. ;)