Well, borrowing from a friend a bit here, but I would suggest the following:
Give the players a nice start point (a town or village with likeable characters). Present various plot hooks to them, that will lead to mini quests around the town. Depending on what the players give priority, new options will open up for the town. They could open up trade, making better items available to them. They could chase down a villain, and bring him in for a great reward. They could investigate something mysterious and possibly very dangerous in the surrounding area. They could investigate what happened to a missing caravan, or missing npc. They could seek out a powerful wizard who is said to live in the area, and ask for his aid. But depending on which quest hook they ignore, you could then escalate that quest.
What I mean with escalation, is that there are some serious negative consequences to ignoring or delaying a quest. Failing to find the missing caravan, could mean the members of the caravan are killed, and the perpetrators becoming a serious threat to the region. The best type of escalation is one that leads to a chain of further plot hooks. And some of these you can come up with on the fly. The point here is not to punish the players, but to raise the stakes, and create an interconnected narrative structure for the quests. Maybe the dragon that recently attacked a town, now lays waste to a nearby city. Maybe a group of orcs has now established a large encampment near the town that the players call home. A quest could escalate to a point where the original plan is no longer an option, and another option will need to be explored. In other words, another plot hook. Or maybe one quest is connected to another in some unexpected way.
If you can find some way to tie the various plot hooks to a larger over arching plot, or to each other, then you have yourself a campaign. Maybe by seeking out the wizard, the players now learn new information about that other dragon plotline, and maybe he can offer them a means to fight the beast, thereby introducing a new plot hook. Seemingly unrelated quests could turn out to be very related indeed. These are all very simple examples of course. You could use these tricks to construct a very complex and intrigueing plot line as well.
I'll give an example from my own campaign:
During a big naval battle, a ship explodes, and several allies of the PC's are thrown into the water, including the brother of one of the PC's. They search the water, but can't find his body, so he must have washed upon that nearby island that everyone says is cursed. The players decide to go on a quest to search the cursed island, and find the missing brother, if he is still alive.
So there you have it. A simple plot hook, that is the direct result of the players actions (the brother wouldn't even have been on the exploding ship had the players not sent him there, straight into a trap), with a twist thrown in by the DM (the exploding ship and missing brother). So how does this lead to further plot hooks?
Well, while on the island the players uncover some ancient ruins. In it they uncover stone murals on a wall, that show how the angelic minions of an evil deity seduced the ancient people on the island, and caused the island to descend into darkness. This is part of the larger overarching plot of their battle against this evil deity, but it is also part of a sub plot regarding what happened to the original inhabitants of the island. Unbeknownst to the players, the islanders are now undead, commanded by powerful evil angelic creatures. Currently however, the players assume the islanders are dead. The corrupted islanders help produce a magical cloud of darkness over the island, that enables the evil deity to enter their world. If the players choose to explore further, they could possibly put a halt to the influence that the deity currently has on their world, and strike a powerful blow against their enemy.
But to do this, they will need to explore the entire island. They will have to brave the treacherous jungle, overcome the ancient defenses of the islanders, and face the powerful angelic monsters that command the now undead islanders. So there's not just a few quests to complete, but a whole lot of exploration and combat to do as well.
And all this because of one missing brother. The brother is fine by the way.
I often don't know where the players will go next. They could ignore the island completely, they could march straight towards the capital and put a stop to the dark cloud, or they could go in the exact opposite direction and run into a corrupted dragon. Will they then kill the dragon, or attempt to free it from its corruption, and possibly make a new powerful ally? Or will they instead focus on delivering the pirate captain that they captured during the battle to an ally of theirs, and gain her loyalty? (they did the latter, and planned to revisit the island later)
This is a great example of how you can tie various mini plots together into one big narrative. What the players decide to do in one quest, may effect the entire campaign, or lead them to new plot hooks. I'm not forcing them to go anywhere, its all them. All I do is throw in a twist or two, and connect the dots.
