may be more difficult, but it's much more satisfying
if you come up with logical ways to maneuver your character
into position to find the clues and red herrings your
plot requires. Repeat after me: Thou shalt not resort
to coincidence, intuition, clairvoyance, or divine intervention.
In a mystery, logic rules. If you do put coincidences
in your story, at least have your point-of-view character
comment on the absurdity of the coincidence. I don't
think that gets you off the hook, but at least it will
keep the reader from dismissing you as a hack."
~Hallie Ephron in Writing and Selling Your Mystery
Novel: How To Knock 'Em Dead With Style