General partition config - I would say 3 partitions minimum for a single OS:
1: mount at /, 8GB
2: mount at /data or /home, size to fill the disk
3: swap space, size is double RAM
If you think you might try different distros, create a couple more 8GB OS partitions.
For 2, mount at /data if you create more than one OS partition. This way, the user settings are retained in the /home directory on the same partition as the OS, and then create directories in /data owned by each user in your system and put their Documents, Images, Music, tmp, etc in there and symlink them into their /home/user directory. Read "man ln" for help symlinking.