Go into Settings>general>storage>manage storage(in middle of page) and check what your space is being used for and delete anything you do not want. If you have a large amount in email you will need to access your email account via safari and delete your emails there. Also if you have just upgraded if may help if you do a reset on your network settings. You do not lose data but you will lose any passwords that are save for wifi and websites. General>Reset>Reset Network Settings. Hope this helps it did with my now very old ipad2