Make yourself a temporary alias for the SD card, test it, then use that so you can’t accidentally get the wrong device. e.g.

MY_SD=/dev/sdc1
ls $MY_SD
dd if=disk.img of=$MY_SD

In this example “ls” is not really a good test, but I’m on Mac so I’m not sure if “diskutil info $MY_SD” would work for you, but sub in any command that you feel gives the confidence that MY_SD points in the right direction. //

If you´re always using the same removable medium, it´s easy to set an udev rule that match this particular device and symlinks (or even rename) it to /dev/whatyouwant

Or even more globally match any USB attached mass storage, for example /dev/sdxn becomes /dev/extUSBxn if you want to.