I have ben lost and still haven't got a sense on this thread so I will just ask....
Are you meaning Nancy Drew type stuff to solve something that is recently happening type of mystery, or the Indiana Jones type mysteris to save the world that are steeped in ancient prophecies and legend that encompass the whole game as the largest plot arch?
I don't think anybody directly answered your question, so here's an answer.
This thread is talking about the "nancy drew" type of mystery. A Whodunnit, or whostoleit.
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Now to something else:
CharlesRyan hit on exactly what I was thinking. In a number of TV/movie "mystery/detective/investigative" stories, clues lead to action, or good clues fall into the investigators lap. There's not a lot of legwork going on.
The red herrings then are in place, to "throw" the forumla off. Basically, run your 1st 2 whodunnits where clue leads to clue leads to bad guy. Then the 3rd game, the clue leads to a red herring/false accusation. Which appears to set the party back, until they re-examine the crime scene/witnesses and find a new clue, or a new informant turns up, or a new body turns up that does reveal a real clue.
Don't waste time on red herrings except to change up from the LAST whodunnit you played. Basically, let the players feel "smart" for solving the last murder, then let them feel stumped. That stumpage let's the bad guy commit another crime, which is where the REAL clue comes in.
It works for James Bond, and nearly every other investigative show.
Another common trope, is that the police detectives are never as observative/charming as the PCs. Witnesses don't say anything to the cops, but they'll talk to the PCs. The cops won't notice that torn note half hidden under the rug, but the PCs will. The cops won't follow up on any of those "random" clues, but the PCs will. And that's how the PCs solve the mysteries, with few if any red herrings. The red herrings are actually for the NPC investigators to stumble over. Label the protagonists in fiction as "PCs" and it's the model you should follow.