Rel
Liquid Awesome
If there was only one type of player then there would be one best way to structure adventures. But that would totally suck so we're blessed with this chaos. 
I start my campaigns off with a few NPC power groups, their motivations and their resources. That gives me an idea of what might happen if nobody else did anything. Then I throw the PC's in the middle of that. Typically whatever happens first is kind of railroady, but hopefully tied in strongly enough to the PC backgrounds that the players are cool with it. That gets the ball rolling.
After that the foremost thing on my mind when planning every session is "How can I take what I've got and make it be as fun as possible for the players?" (Note that I said players. What's fun for the players isn't always, or even frequently, fun for the characters.)
Great games are not great because of how the adventure is structured. Great games are great because everybody had a lot of fun. Knowing your players and knowing how they have fun is the key to great games.
Now, that said, you need SOME kind of structure to enable that fun. For me what works best is that I typically end every session by clarifying what it is that the group plans to do the next session. "So you guys are going to explore the Spider Pits in the hopes of finding the Eight Faceted Eye of Grimdol, right?" If that's what they agree to then that's what I prepare. If the next session they say, "Hey, let's go back to town and root out the Assassin's Guild instead!" then I say, "Hey, let's play Rock Band tonight instead of gaming!" But usually they don't do that. They stick with what they said they were going to do because they know that doing otherwise kind of makes them dicks. And they aren't dicks.
Designing then becomes all about catering to their playstyles in both a generalized and a specific way. I'm sometimes more and sometimes less formal about writing this down (I've played with the same basic group for a long time). But when I'm formal about it, it looks something like this:
Buttkicker - He'll love the combats at the start and especially the big battle at the end of the session. Make sure not to lose him during the heavy story part in the middle of the session by emphasizing the epic battles that Grimdol engaged in.
Super Coolness Guy - There's no way they can get past the magically locked door into Grimdol's Tomb without him. Emphasize that. Also make a point to mention the magic runes inscribed on the Sarcophagus and point up that the College of Wizardry will be THRILLED to have a copy of those, increasing his standing there.
Storyteller - She might tend to get a little bored in the early battle when it feels just like a dungeon crawl. Have the bad guys go after her character so that she stays engaged. She'll LOVE the part in the middle when they get to read the Chronicle of Grimdol and that'll add lots of interest to the final battle when they have to face Grimdol's Spider that they read about earlier.
Casual Gamer - He's mostly along for the ride but make sure and pass him a note about how part of the Chronicle references the Lost Gem of the Shire as being one of the artifacts that Grimdol stole during his reign of terror. That will point to one of his adventuring goals without forcing him into the spotlight.
Obviously I'm referencing some other events: An introductory "fight their way into the dungeon" fight, the revelation of a bunch of story information, and an epic final battle against a BBEG. But organizing combat information or maps or whatever is handled however works best for you as a GM. The important part is where to focus my attention on making sure each player has fun during the session. I'm noting pitfalls where they might tend to lose interest and how to mitigate that. And I'm also noting what are likely to be the highlights and how to enhance those as much as possible.

I start my campaigns off with a few NPC power groups, their motivations and their resources. That gives me an idea of what might happen if nobody else did anything. Then I throw the PC's in the middle of that. Typically whatever happens first is kind of railroady, but hopefully tied in strongly enough to the PC backgrounds that the players are cool with it. That gets the ball rolling.
After that the foremost thing on my mind when planning every session is "How can I take what I've got and make it be as fun as possible for the players?" (Note that I said players. What's fun for the players isn't always, or even frequently, fun for the characters.)
Great games are not great because of how the adventure is structured. Great games are great because everybody had a lot of fun. Knowing your players and knowing how they have fun is the key to great games.
Now, that said, you need SOME kind of structure to enable that fun. For me what works best is that I typically end every session by clarifying what it is that the group plans to do the next session. "So you guys are going to explore the Spider Pits in the hopes of finding the Eight Faceted Eye of Grimdol, right?" If that's what they agree to then that's what I prepare. If the next session they say, "Hey, let's go back to town and root out the Assassin's Guild instead!" then I say, "Hey, let's play Rock Band tonight instead of gaming!" But usually they don't do that. They stick with what they said they were going to do because they know that doing otherwise kind of makes them dicks. And they aren't dicks.
Designing then becomes all about catering to their playstyles in both a generalized and a specific way. I'm sometimes more and sometimes less formal about writing this down (I've played with the same basic group for a long time). But when I'm formal about it, it looks something like this:
Buttkicker - He'll love the combats at the start and especially the big battle at the end of the session. Make sure not to lose him during the heavy story part in the middle of the session by emphasizing the epic battles that Grimdol engaged in.
Super Coolness Guy - There's no way they can get past the magically locked door into Grimdol's Tomb without him. Emphasize that. Also make a point to mention the magic runes inscribed on the Sarcophagus and point up that the College of Wizardry will be THRILLED to have a copy of those, increasing his standing there.
Storyteller - She might tend to get a little bored in the early battle when it feels just like a dungeon crawl. Have the bad guys go after her character so that she stays engaged. She'll LOVE the part in the middle when they get to read the Chronicle of Grimdol and that'll add lots of interest to the final battle when they have to face Grimdol's Spider that they read about earlier.
Casual Gamer - He's mostly along for the ride but make sure and pass him a note about how part of the Chronicle references the Lost Gem of the Shire as being one of the artifacts that Grimdol stole during his reign of terror. That will point to one of his adventuring goals without forcing him into the spotlight.
Obviously I'm referencing some other events: An introductory "fight their way into the dungeon" fight, the revelation of a bunch of story information, and an epic final battle against a BBEG. But organizing combat information or maps or whatever is handled however works best for you as a GM. The important part is where to focus my attention on making sure each player has fun during the session. I'm noting pitfalls where they might tend to lose interest and how to mitigate that. And I'm also noting what are likely to be the highlights and how to enhance those as much as possible.