Resources
Where to Find a Local Writing Group
MeetUp.com - www.meetup.com/find/writing
Local Library
Local Bookstore
Organizations listed below may have a local chapter near you
Organizations Open to Unpublished Authors
These organizations all accept published authors, but are also open to unpublished authors, often as Associate Members. (Please note that I don't edit books in all of these genres.)
American Christian Fiction Writers (ACFW) - www.acfw.com
The Authors Guild (AG) - www.authorsguild.org
Historical Novel Society - historicalnovelsociety.org
Horror Writers Association (HWA) - http://horror.org/
International Thriller Writers (ITW) - http://thrillerwriters.org/
Romance Writers of America (RWA) - www.rwa.org
Romantic Novelists' Association - romanticnovelistsassociation.org
Sisters in Crime (SinC) - www.sistersincrime.org
Society of Children's Book Writers and Illustrators (SCBWI) - https://www.scbwi.org/
Resources for Finding a Literary Agent
Association of American Literary Agents *(AALA) - aalitagents.org
(Formerly the Association of Authors' Representatives, Inc. (AAR))
Literary Marketplace (LMP) - www.literarymarketplace.com
(Also available in print at your local library)
Publishers Marketplace - www.publishersmarketplace.com
(membership required)
QueryManager - querymanager.com
QueryTracker - querytracker.net
Writers Beware - General advice provided by SFWA about literary agents can be found here.

Organizations for Published Authors Only
American Society of Journalists and Authors (ASJA) - asja.org
Mystery Writers of America (MWA) - mysterywriters.org
Science Fiction & Fantasy Writers of America (SFWA) - www.sfwa.org
Western Writers of America (WWA) - westernwriters.org
Resources for Independent Authors
Independent Book Publishers Association (IBPA) - www.ibpa-online.org
Ingram Spark - www.ingramspark.com
Kindle Unlimited - kdp.amazon.com
Apple Books for Authors - authors.apple.com
BISAC Code List - bisg.org/page/BISACEdition
See my blog post How BISAC Codes Can Help Your Book
Book Festivals & Conferences
This is a list in progress of significant book festivals and conferences for writers in the United States, with hyperlinks to their websites. I have only attended a few of these events personally, but have heard of many of them. I've tried to include a range of locations and genres. Most offer panels and workshops where you can learn more about publishing and develop your craft as a writer, as well as opportunities for published authors to promote their books through speaking opportunities and book signings.
February
San Francisco Writers Conference (San Francisco, CA)
March
Association of Writers & Writer Programs (AWP) Conference (location varies)
Left Coast Crime Mystery Convention (San Diego, CA)
National Black Writers Conference (Brooklyn, NY)
Sleuthfest (Boca Raton, FL)
Tucson Festival of Books (Tucson, AZ)
Virginia Festival of Books (Charlottesville, VA)
April
Los Angeles Times Festival of Books (Los Angeles, CA)
The Muse & the Marketplace (Boston, MA)
Ohioana Book Festival (Columbus, OH)
Pikes Peak Writers Conference (Colorado Springs, CO)
Publishing in Color (on-line for 2021)
May
Atlanta Writers Conference (Atlanta, GA)
Bay Area Book Festival (Berkeley, CA)
BookCon (connected to BEA, New York, NY)
Book Expo America (BEA) (New York, NY)
Books in Bloom (Eureka Springs, AR)
Malice Domestic (cozy mysteries, Washington, DC area)
June
Jackson Hole Writers Conference (Jackson Hole, WY)
Santa Barbara Writers Conference (Santa Barbara, CA)
Western Writers of America Convention (location varies)
July
Romance Writers of America Conference (location varies)
Sewanee Writers Conference (Sewanne, TN)
Thrillerfest (New York, NY)
August
Breadloaf Writers Conference (Middlebury, VT)
Killer Nashville International Writers' Conference (crime fiction/thrillers, Nashville, TN)
Mississippi Book Festival (Jackson, MS)
September
American Christian Fiction Writers Conference (location varies)
October
Black Authors & Readers Rock (BARR) (Oxxon Hill, MD)
Bouchercon World Mystery Convention (location varies)
Brattleboro Literary Festival (Brattleboro, VT)
Moonlight & Magnolias Conference (hosted by Georgia Romance Writers)
National Black Book Festival (Houston, TX)
South Dakota Festival of Books (Brookings & Sioux Falls, SD)
Southern Festival of Books (Nashville, TN)
Texas Book Festival (Austin, TX)
West Virginia Book Festival (Charleston, WV)
November
Baltimore Book Festival (Baltimore, MD)
Kentucky Book Festival (Frankfort, KY)
Miami Book Fair (Miami, FL)
Portland Book Festival (Portland, OR)
WriterFest Nashville (Nashville, TN)