Show don't tell can be hard when you don't know the minutia of how things are done. It's so easy to get it wrong even when you try to play it safe. Lee Lofland's post is of course not comprehensive, but if you have a cop collecting evidence, there's some nice detail here.
Got a story that includes the FBI? The FBI is willing to talk to you.
Every writer I know struggles with the best way to start their novel, so this is an excellent reminder of what to watch out for.
Lee Lofland often posts about those little details of police procedures. Here are some nice ones that might inspire an idea or two and maybe add some authenticity to a story.
Emma Darwin's blog The Itch of Writing is almost a master-level course in writing. It comes right to my inbox whenever there's a new post. This one talks about a topic that makes a lot of authors uncomfortable: writing sex