Understand sequential art. If you haven't already, pick up Scott McCloud's book "Understanding Comics." It is a vital book in grasping the science, and philosophy, behind this versatile medium. After that, read "Making Comics" by the same author (see Resources below).
Develop synergy with your creative partners. Even if you are working by yourself, this is a good idea. Figure out how you want your book to look and feel, what are you trying accomplish and how will you do it. For example, if you are trying for a comedic story, you might want your artist to draw the characters more like cartoons than portraits.
Write your script. If you are lost on what one looks like, go to the Comic Book Scripts website (see Resources). The scripts on the page are actual, official scripts of published comics. It might help to find an issue of one of these comics so you can see how the artist translated the writer's words into pictures. Comic book scripts vary greatly in style, but it never hurts to be overly descriptive.
Draw, color and letter the comics. Of course, this step is condensed, so expect the process to take awhile. Make sure the art is at its absolute best. Consistency and professionalism are more important than style or talent.
Publish the comic. This is a multistep process in itself and of course requires money. First you want to print the comic; this can be done at a printing store--Kinko's, for example. If you live near a large university, oftentimes they have a printing department, and you might be able to work out something with them. Also, you probably want to work out copyright issues at this point to protect your art. You can get details on that at the Copyright website (see Resources).
Distribute the book. Now that you have a finished produc, you want people to appreciate your hard work, so get it on the shelves! The most basic start to this step is to give some free comics to friends or interested parties. After that, go to local comic book shops and see if they'll let you put a few copies there. At this point, you shouldn't be worried about making your money back but instead about getting people interested in your art.