Now that I've pointed to a website I'll give you some of the advice I have taken from rpg.net and my own experience:
1: Say Yes Or Roll the Dice
Whenever a player asks if they can do something you have two possible responses: "Yes." or "Roll." Now, there is nothing forcing you to make the roll easy or even possible. The point is to empower your players. By either permitting the course of action or giving them a target number (or difficulty, or whatever the system uses) you give the players a sense of active participation. Most importantly, you can point out how they can do things they might not be able to now.
For example: "Ah, you want to convince the Death God not to eat your souls? What's your diplomacy rank again? I hope you can hit a target number of 30..." or "You're going to cold start the spaceship to escapethe exploding space station? Did you put ranks in Pilot? Well, its difficulty 4 then..."
Other acceptable answers to the question of "Can I...?" are: "Yes, but..." and "Yes, if..." The only unacceptable answer is "No."
2: The Game Is About The PCs
Each PC should select a Motivation. This is a primary plot point they want to accomplish during the game. For example a Motivation can be "Find the six-fingered man who killed my father and have my revenge." or "Discover the secrets of Atlantis" or "Get laid." Whatever.
The key here is that these are things that both the player and the character are interested in. Once you have all these (which should be the FIRST thing you do) you cna build your campaign or adventure around those Motivations. Make certain that they are not contradictory. For example "I want to reform the local legal system to be more fair" and "I want to explore ancient ruins full of evil monsters" would be hard to place in the same campaign. AS GM, feel free to veto ideas you feel would be bad for the group.
3: Don't Roll The Dice Unless You Accept the Consequences
If the result of a failed roll would spoil the fun of the game don't roll. Just declare whatever outcome would be the most fun (see Rule 1, however) and go with that. Honestly speaking, the only time you should be rolling the dice is when both outcomes of the roll would make an interesting story.
Example: The PCs are breaking into a mansion to steal incriminating evidence. Only have them roll to sneak if the results of failure would be interesting (getting caught is usually interesting) and onyl have them roll to investigate if the results of failure would be interesting (failure to find the evidence means the bad guy gets to continue hassling the PCs). If locating the evidence is crucial to continuining ythe adventure, then just have them find it and go from there.
4: Too Much Preperation Leads to Heartache
Your adventures are not novels, or movie scripts or even video game levels. You can not expect the PCs to follow your ideas.
Ideally your planning should involve the names of major NPCs and their motivations, an idea of the primary locations and other stuff. All of it should be background information. You should know the PAST of the setting, but not the FUTURE of it. The PCs are going to decide the future, not you.
For example, instead of having a plan for how the major villian should be defeated, you should have a plan for how he intends to succeed. Then the PCs show up. If they disrupt his plans, great! He'll either be defeated or (more likely) will come up with a new plan. If they fail to intervene... also great! Now the badguy has succeeded, and its up to the PCs to deal with the consequences of this.
Edit: 6: The Best Solution To Every Problem Is the PCs
No matter the campaign goal, the best way to accomplish it just happens to be whatever skills the PCs are best at, imagine that! To put it more bluntly, design your campaogn so that the PCs have an excellent chance of triumphing with whatever skills they focused on. One of the PCs focused on Pilot skill? Funny how there is always a need to chase down villians in planes! One of the PCs maxed out his Carpentry skill? Good thing that the only way to save those freezing children is to build them a new house! One of the PCs took telepathy? The fiendish Dr. Distaster's only weakness is his inability to sense telepathic intrusion!
Now, this doens't mean you can't throw curves at the players, but generally only at their choice. If the PCs choose to take up a challenge that their skill set doens't handle, let them fumbel around and fail. But every challenge YOU create should be custom built for the PCs to overcome, and for them to look cool doing it.
I have some more, but its very specific to certain game systems and genres.
---------------------
Epsilon
1: Say Yes Or Roll the Dice
Whenever a player asks if they can do something you have two possible responses: "Yes." or "Roll." Now, there is nothing forcing you to make the roll easy or even possible. The point is to empower your players. By either permitting the course of action or giving them a target number (or difficulty, or whatever the system uses) you give the players a sense of active participation. Most importantly, you can point out how they can do things they might not be able to now.
For example: "Ah, you want to convince the Death God not to eat your souls? What's your diplomacy rank again? I hope you can hit a target number of 30..." or "You're going to cold start the spaceship to escapethe exploding space station? Did you put ranks in Pilot? Well, its difficulty 4 then..."
Other acceptable answers to the question of "Can I...?" are: "Yes, but..." and "Yes, if..." The only unacceptable answer is "No."
2: The Game Is About The PCs
Each PC should select a Motivation. This is a primary plot point they want to accomplish during the game. For example a Motivation can be "Find the six-fingered man who killed my father and have my revenge." or "Discover the secrets of Atlantis" or "Get laid." Whatever.
The key here is that these are things that both the player and the character are interested in. Once you have all these (which should be the FIRST thing you do) you cna build your campaign or adventure around those Motivations. Make certain that they are not contradictory. For example "I want to reform the local legal system to be more fair" and "I want to explore ancient ruins full of evil monsters" would be hard to place in the same campaign. AS GM, feel free to veto ideas you feel would be bad for the group.
3: Don't Roll The Dice Unless You Accept the Consequences
If the result of a failed roll would spoil the fun of the game don't roll. Just declare whatever outcome would be the most fun (see Rule 1, however) and go with that. Honestly speaking, the only time you should be rolling the dice is when both outcomes of the roll would make an interesting story.
Example: The PCs are breaking into a mansion to steal incriminating evidence. Only have them roll to sneak if the results of failure would be interesting (getting caught is usually interesting) and onyl have them roll to investigate if the results of failure would be interesting (failure to find the evidence means the bad guy gets to continue hassling the PCs). If locating the evidence is crucial to continuining ythe adventure, then just have them find it and go from there.
4: Too Much Preperation Leads to Heartache
Your adventures are not novels, or movie scripts or even video game levels. You can not expect the PCs to follow your ideas.
Ideally your planning should involve the names of major NPCs and their motivations, an idea of the primary locations and other stuff. All of it should be background information. You should know the PAST of the setting, but not the FUTURE of it. The PCs are going to decide the future, not you.
For example, instead of having a plan for how the major villian should be defeated, you should have a plan for how he intends to succeed. Then the PCs show up. If they disrupt his plans, great! He'll either be defeated or (more likely) will come up with a new plan. If they fail to intervene... also great! Now the badguy has succeeded, and its up to the PCs to deal with the consequences of this.
Edit: 6: The Best Solution To Every Problem Is the PCs
No matter the campaign goal, the best way to accomplish it just happens to be whatever skills the PCs are best at, imagine that! To put it more bluntly, design your campaogn so that the PCs have an excellent chance of triumphing with whatever skills they focused on. One of the PCs focused on Pilot skill? Funny how there is always a need to chase down villians in planes! One of the PCs maxed out his Carpentry skill? Good thing that the only way to save those freezing children is to build them a new house! One of the PCs took telepathy? The fiendish Dr. Distaster's only weakness is his inability to sense telepathic intrusion!
Now, this doens't mean you can't throw curves at the players, but generally only at their choice. If the PCs choose to take up a challenge that their skill set doens't handle, let them fumbel around and fail. But every challenge YOU create should be custom built for the PCs to overcome, and for them to look cool doing it.
I have some more, but its very specific to certain game systems and genres.
---------------------
Epsilon