The following is text from the "Hero System" fifth edition, by Steven S. Long (copyright 2001). This is selected text which reveals the authors' view of what roleplaying is and the responsibilities of GM and players.
Note that the 5th edition Hero System has no introduction to role-playing, or definitions of basic concepts. It is written as a toolkit for experienced gamers. However, there is advice to the GM which reflects its ideas.
Gamemastering chapter, page 341:
Roleplaying games are about interactive storytelling: the GM and the players work together to create their own story, rather than reading or watching one created by someone else. Therefore a good GM will learn about the literary devices that make stories work, and use them.
Gamemastering chapter, page 343:
As a GM, you'll find it all too easy to get caught up in your story, the great story you've got planned out, and to make sure you tell that story -- no matter how many improbable plot twists you have to throw in or player actions you have to ignore to make sure that your story takes place. But the player characters are the focus of your story, and therefore they and their players are the most important elements in your story. You should slant the story to suit them, not the other way around. Learning how to do this, and do it well, is one of the hardest things about good GMing.
The first and most important thing to do is to plan stories which your players and PCs will want to participate in without having to drag them along by ring through their noses. There are plenty of ways to do this. First, work the PCs' Disadvantages into the story, as discussed above -- if it's someone's archenemy, girlfriend, or Vulnerability that's involved, the PCs will have incentive to get in on the action. Second, make sure that each PC has his moment in the sun -- a scenario featuring him as the main character. One of the standard ways of doing this is to bring something from that character's past back to haunt him -- an old enemy he thought was dead, a long-lost love, anything like that. If the player has developed a "background story" for his character, then incorporate part of it into a scenario, allowing the PC to learn more about himself.
Second, learn to adapt your stories to the players' cool and interesting ideas. Many a GM rejects ideas that the players come up with in the middle of a story, simply because the players' idea is different from what he has in mind. It doesn't matter if the players' solution to the mystery or combat situation is as good as, or better than, his own; he's determined to follow through with his story, and damn the consequences. This is wrong. Remember, your story focuses on the players and their characters. If they come up with an idea which is as good as (or better than) what you had planned or thought they would do, and you can adapt the story to conform to their ideas without ruining other parts of it or making major changes to the campaign world, do it. The players will gain a great sense of accomplishment and heap praise upon you for your excellent GMing -- and you didn't have to do a thing but listen to them and react accordingly.
Similarly, when a player asks, "Is there a so-and-so nearby?", he usually has some neat idea in mind for using it, something you'll likely enjoy. Unless it's impossible for that object to be in that area, tell him yes. He'll feel like he's contributing to the story and the world, and you get to have fun seeing just what he has in mind.
However, don't think you always have to change to suit the players -- if it would be too much trouble, or would cause major changes in the world or the NPCs, don't do it. Sometimes the players' ideas are based on misconceptions about the world and its characters, or they're acting on less than all the relevant information, or they just plain make mistakes. In those situations, stick to your guns and follow through with the story as planned.
Third, include opportunities for both role-playing and combat in your games. Few players or PCs want exclusively one or the other in their games. Think about your favorite stories, the ones you really like -- how many of them are just combat, or just role-playing? Probably none; a good story or movie mixes in both elements. Your games should, too.
One good way to foster roleplaying is to use bluebooking. Bluebooking is nothing more than writing out roleplaying and conversations between characters, rather than acting them out (usually this takes place between game sessions). Sometimes players feel uncomfortable acting out some scenes (such as love scenes), or will want to keep some scenes private. This presents a perfect opportunity to use bluebooking. Bluebooking also has the advantage of permanence; you keep the written records of what went on, and can use them to create future scenarios.