As previously stated, move or transfer items such as images and media files to your computer (via iTunes).

Clear the cache, cookies, history, and other data in your browser app. If your browser starts to perform strangely, such as lagging, freezing, or crashing, this is a must-do. Carry on with your other third-party programs in the same way.

Call logs should be deleted. Call logs take up space in your internal memory, so if you're not using them, you might as well delete them.