Assuming your phone is already rooted with Towelroot, Link2SD probably works and you can sort by total size, etc., to decide what to move. The paid version allows you to symlink everything, but you can save a lot of room with the unpaid too. First, you have to create an ext4 second partition on your microSD card; you can do that on your PC if you have an adapter and SD-card slot, of course, but the easiest way for rooted phones is install AParted from the Playstore and use AParted to create a second partition on the microSD card that is formatted ext4. After the second partition is created on the microSD, open Link2SD and Link2SD will install the scripts that mount the ext4 microSD partition at boot. Reboot, and you can then use Link2SD to move the data and symlink, which saves you a ton of room on your internal storage. I haven't needed to do it with the LG Volt yet, but I definitely had to on my old LG Optimus F3. Good luck.