The only thing you could easily move to an SD card (and is probably not recommended) or delete without losing any application personalization settings would be the %USERPROFILE%\AppData\Local\Temp folder. My AppData folder is about 4GB and that %Temp% folder is only 8MB. I believe your Windows Store applications user settings are stored in the "Packages" folder. which is 3.5GB for me; so I don't think you want to delete that. You can decrease the size of the Windows page file which is just over 2GB on my Surface 2 to gain some more space. Though some don't recommend it because it could cause some system instability, I've seen the Surface 2 run just fine with no Windows page file. Of course you always have Disk Cleanup, and make sure you select everything it finds, the Windows Update Backups that allow you to roll back updates can become quite large.