You do need to be careful, but you can check for errors after editing /etc/fstab by running the command sudo mount -a. With the drive attached but not mounted. (Also good practice to use the UUID of the drive in the fstab entry)
That command runs through etc/fstab and attempts to mount everything it is instructed to mount if it is not already mounted. And if there is an error it will let you know.
If you run sudo mount -a and you get no output in the terminal, then there are no errors, your drive should now be mounted, and you should be fine for reboots and it should mount on startup as expected.