I get a "memory full" message ："There is not enough available storage to download "Skype" . You can manage your storage in settings."

The biggest storage are usually photos and videos, but there's also the infamous others, which can take up to 10 GB of space .
Deleting a few pictures and movies might help me out of a jam, but if you're continually getting that "not
enough available storage" warning like me, please help me out.

I found this Macgo free iphone cleaner tool on the Internet. Who can give me a tutorial about it？

Never heard of iPhone cleaner before

1.Go to settings-General-Usage , to manage your storage. Simple.

2.Double click your homepage button to reduce the open windows by swiping them up one at a time.

3. Delete some apps.

4. Check your App Store and delete the apps waiting to be updated but not needed. Those take up spaces too.

5. Have you updated to iOS 8.3?

Try that and see.