There's a handy postcard with standard commands and a strategy guide for beginners. It's written by Andrew Plotkin and designed by Lea Albaugh, and you can use it as a cheat sheet while you play: http://pr-if.org/doc/play-if-card/
You can also try typing HELP in the game itself to see if the game offers any instructions.
There are even some interactive fiction games that have a tutorial mode, for instance, The Dreamhold.
Here are some other games on IFDB that have been tagged "tutorial mode": http://ifdb.tads.org/search?searchbar=tag%3Atutorial+mode