I have always just used growisofs on its own. Growisofs actually uses mkisofs to create an iso, so there is no need to use the two separately. The command I use is:
growisofs -Z /dev/dvd -R -J /some/files
-J is for Joliet, which allows long file names on Windows machines.
-R is similar, but for Linux.
This is from the man page for mkisofs.