The Engine, the how to message board, is going away soon, and with it a treasure house of knowledge, in between the pictures of girls in their underwear. Caleb Monroe’s post onhow to pitch and make submissions to editors deserves to be archived in full:

1.) The Pitch by Warren Ellis
2.) Creating Comics Step-By-Step: The Pitch by Steven Grant

As for etiquette:
Proposal Etiquette by Dan Wickline with various editors
Getting Your Submission Read by various editors
On her blog, SLG editor Jennifer DeGuzman does a series where she goes through their submission slushpile and points out people’s mistakes.
Top 10 Tips for Comic Book Writers (pertains especially to preparing a proposal) by Image Shadowline editor Kris Simon.

“The Rule of Four Ps” when submitting by C.B. Cebulski

In fact, if anyone ever asks us how to break into comics again, we’re just going to cut and paste this again and again and again.

Extra: Justin Jordan’s list of archived posts. Get it quick.