One: Don't force the story on the player. I don't care how intricately crafted the characters are, how deep and thrilling the plot is, or how much you paid for voice actors. Sometimes I just want to play the game. (Typically, I'll want to play a second time and already know the story.)
I won't accept that the storyline is a necessary part of gameplay either (except for the RPG genre). If a game is not good enough to stand up purely on the game mechanics, it's not a good game. If you have put so much effort into the story, you can't bear the thought of players missing the storyline, then write a book/make a TV series/film.
Unskippable cutscenes are the most obvious and most common version of this, but it is also possible to achieve by not allowing the player to move on until they discover some plot point. RPG's are allowed to do this.
Everything else: if you're insistent on a player knowing a certain piece of story, mark the place to find it on the map, thank you. Cutscenes in and of themselves are not too bad, but keep them concise. It's much better from the players point of view if we find out the information by playing ourselves, but not always possible.
Notable offenders: Assassin's Creed
Surprisingly good: Knights of the Old Republic (as long as you get the bit about the Star Maps, you can play this virtually ignoring the storyline.)
Two: Don't be repetitive. Management sims are exempt from this. This is about not forcing the player to do the same thing over and over. There are many ways this can come about.
The simplest is save-points. Everyone has played a game where it saves, then has a cutscene, then a hard boss battle. Every failed attempt at the boss battle replays the cutscene.
Assassin's Creed is odd here, in that it does this well for pickpocketing (retrying after a failure skips the dialogue) but badly for informants. Every time you fail, you have to hear the same dialogue telling you why he needs you to do whatever-he's-asking-you-to-do, while I stand thinking "I know, I know, let me get on with it!"
A more subtle variant is found on the "save citizen" challenges. After every one the game makes you stand around and listen to the saved citizen thanking you, all the while you should be running from the scene. Then, the reward (scholars, or vigilantes) are focussed on before you can start fleeing. The whole process takes almost a minute. Particularly annoying here is making a big point of showing you the scholars/vigilantes you won, since they appear on the map.
This is also an excellent reason to include fast-travel between important points on the map.
Notable offender: Assassin's Creed
Surprisingly good: Half-Life 2
Three: Let the player dictate the pace. Some players like blasting through levels as fast as possible, others like to go slowly and take it all in. The latter do badly at racing games. Assassin's Creed actually gets this very right. While exploring, you have four speeds available to you, depending on whether you're sneaking up on a guard or running like hell from one. However, as Desmond you are limited to walking slowly around the office, mostly unable to interact with things.
Notable offender: Assassin's Creed (as Desmond)
Suprisingly good: Assassin's Creed (as Altiar)
Zero: Keep the player in control. In essence, all the other rules on the list come down to this. We play games because we like to play. Points where the game wrests control from the player are frustrating and totally break immersion (since we're suddenly aware of the limitations of the medium).
This is a really broad rule applying to all sorts of things. For example: in Assassin's Creed there are drunk who will, given the opportunity, wallop the player one and beggars who will just harass you.
This isn't too bad, except there's nothing you can do about it. You lose health (or synch) for retaliating. Even worse is that the drunks have a horrible tendency to totally blow your cover. Simple things that could be done about this are: let us give a few coins to the beggars; if a soldier spots a drunk taking a swing, have him come over and arrest the drunk. It would be really satisfying to see the soldiers on your side for once.
Notable offender: Assassin's Creed
So come on, designers. When are we going to see an end to needlessly poor games?