This list was composed off my experiences in writer Sonic the Hedgehog, but the process remains generally the same across titles, publishers and mediums.
1) The writer comes up with the concept for the story. (S)he prepares a springboard for the editor: a 1-2 paragraph synopsis of the story highlighting the key points. (sometimes the editor will propose the initial concept)
2) With the springboard approved, the writer creates the breakdown – a page-by-page overview of the issue. Each page is described in a sentence, essentially keeping things to “one idea per page.” This allows for easy review and restructuring if necessary.
3) With the breakdowns approved, the writer then produces the first draft of the manuscript. This details the setting, characters, action and dialogue for each panel on every page. The writer also writes in panel placement to set the pacing of the issue.
4) The manuscript is reviewed and revised until it meets editorial approval. It then must meet the licensor’s approval.
5) With the manuscript fully approved, it moves on to the penciller. The penciller follows the directions from the script to produce the pages. These are sometimes scanned and emailed for approval before the pages are put in the mail.
6) With the penciled pages approved and finalized, the inker takes over. The inker puts down the final lines, the line weights, shadows and texture.
7) The letterer receives the inked pages and places the word balloons and text. Some of the sound effects are added at this stage, while some were drawn in by the penciller and inker.
8) The colorist follows the catalog of established colors to finish the images, adding shading and highlights for greater depth and appeal.
9) With the comic complete, it’s sent to the printers. From there, it is distributed to the subscribers and retailers.
It should be noted that every step of this process is overseen and approved by the editor.