The best way to learn about writing is with practice and practice and more practice. Read books on writing and work with a critique group. Attend writing conferences and mystery conventions. The information found there is invaluable.

Here are links to some mystery conventions and writing conferences:

www.bouchercon.com

http://www.mwa-florida.org/sleuthfest.htm

http://lcc2007.com

http://www.malicedomestic.org/

http://www.loveismurder.net/

http://www.omaha.lib.ne.us/mayhem/

http://bloodywords.com/bw/index.html

http://www.partnersincrimeboise.com/murder.htm

http://www.deadlyink.com/conference.html

http://www.thrillerwriters.org/thrillerfest/

http://www.conmisterio.org/guests.html