documentation: add a tips section

README.md

@@ -75,3 +75,36 @@ Umount the home filesystem.
 ## status
 
 Tells if the mount is currently done.
+
+# Tips
+
+## I configured something in a GUI program, how do I know what changed on disk?
+
+If you want to add a file to the persistent area after a change,
+you may want to know exactly what changed on disk to add the file
+or directory to your configuration file.
+
+Using `find` it's easy to scan all the files from the ramdisk
+(excluding the symbolic links) and order them by date of change.
+
+This can be done with `find -x ~/ -type f -exec ls -altr {} +`, the
+last files are the most recently modified one.
+
+## Beware file loss
+
+When using this way of life, you need to remember every changes
+that doesn't belong in the persistent areas will be lost. For
+example, this will happen for every new files or directories at the
+root of your $HOME.
+
+Impermanence requires the user to be aware of what files must stay
+over time, this is the point of impermanence after all.
+
+## I want to make a new file/directory persistent
+
+If you are using your system and want to keep a newly created file
+or directory, move it to your persistent area at the correct place
+and create a symbolic link, this will allow a drop-in replacement
+without rebooting.
+
+Then, update your configuration file to add the new entry.