Here are the shortcuts that were of utmost importance to get me productive with KSH:

“stty erase ^?” to remove the ‘^?’ symbol when the backspace key is pressed.

“Ctrl-p” shows the previous command that you typed, pressing several time will get you sequentially to older commands

“Ctrl-n” shows the next command in case you used “Ctrl-p”, i.e. navigates forward

“Ctrl-b” moves the cursor back one character

“Ctrl-f” moves the cursor forward one character

Here is a screenshot of a table that contains most of the shortcuts

Note: Not all of them work, like the reverse search, have no idea why yet.

Source: http://www.bigsmoke.us/readline/shortcuts