Insufficient storage on iPhone causing issues

My iPhone is almost completely full and I don't know what to do about it i purchased more cloud storage and it was not worth the money because I can't use the phone to update the new iOS and it is completely driving me insane and on top of that it is still acting like something or someone else is trying to get control of it and not letting me use it and my photos keep duplicating and it's taking all of my data and space so ridiculous and it's just letting me back up to the cloud and I can't even see anything on it and I don't know what to do anymore

[Re-Titled by Moderator]