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The overarching structure of my current campaign relies a lot on discovery. My players are placed in an open world that they can explore more or less freely, but in order to make progress in whatever they're trying to do they'll have to uncover secrets: political secrets, historical secrets, metaphysical secrets, etc. I'm struggling with figuring out how much information to give them at once. Too little information at the start and they don't catch my plot hooks; too little information once they're on the trail of something and they get disheartened or distracted and give up; too much information and I don't have a campaign, just a series of expository monologues about a fictional world punctuated by bouts of imaginary violence.
In some cases, it's not immediately obvious that there are secrets to be uncovered. My players aren't the sort to go haring after everything that looks a tiny bit out of place anyway, and they tend to have a hard time remembering even the things that did pique their curiosity from one session to the next. I don't want to clobber them over the heads with a big flashing sign that says "SEE THIS THING HERE? YOU SHOULD BE LOOK INTO IT. MAYBE START ASKING AROUND, IT'LL PROBABLY BE IMPORTANT". I'm concerned that dropping big obvious mystery hooks in front of them would cheapen their sense of both discovery and freedom; I'm trying to run this as a more open-world campaign rather than leading them by the nose down a linear plot of my own choosing.
Part of letting them discover things themselves means that I'm not just feeding them information, even when they've identified something they're interested in. They have to work for it. Figure out the right questions to ask of the right people, maybe go to the right place, overcome some challenges or encounters. I've been trying to encourage them to be more curious and ask more questions, but if they aren't getting rewarded for their curiosity they tend to give up fairly quickly. On the other hand, sometimes they pursue duds - not every street corner hobo knows the true origins of the elves or whatnot, and even some very knowledgeable people have a good reason to want to keep their secrets. I'm wary about opening the flow of information too wide because some things really shouldn't be uncovered until later in the campaign, either because they'd short circuit a lot of the other conflicts and plot points in the world or because the party isn't high enough level to poke at those cans of worms yet.
Reading my own question, it seems like the question I ought to be asking is: how can I turn the process of discovery into a proper quest - one that grabs at the players' attention without feeling thrust upon them, and captures their interest enough to motivate them to keep going through a longer form discovery process while still providing enough challenge that I'm not just dumping exposition on them?