Decide which medium you're using. If you're going the classic photocopied route, you'll need little more than stacks of advertisements, magazines or other sources of printed images. Choose however many images you imagine using, and begin cutting them out of your stack of source materials.
Arrange your chosen images into a sample layout, taking care to leave prominent space for the band's name, followed by the relevant time, date and place details. Once you've decided where those elements will go, start gluing or taping them into place.
Draw greater contrasts between each image that you use--mix up styles, sizes and colors to grab a viewer's attention. The starker the contrast, the greater the chance that someone will look twice.
Leave enough room for images or details that you add with a drawing pencil, pen or Magic Marker. Stack them in sequential order--from top to bottom, for example, with the smallest type first--taking care that your layout doesn't overwhelm the key details about the show.
Photocopy however many flyers you need to get the promotional point across--don't lowball yourself, but don't run out more than the band and its army of volunteers could spend time posting. Costs can add up quickly, so using a friend's machine, or one that you can surreptitiously use at your job--is a good starting point, so long as you realize this won't last forever.
Map out your layouts on a computer--preferably through recognized design programs like Adobe, or Pagemaker--to ensure a more consistently professional look. Sketch out a rough design using the appropriate drawing function, then fill in the details as you go (including font sizes and styles, colors and highlights).
Draw a photo box, if you're using a program like Quark Xpress, and click on the image you're seeking to use. Drag and drop it into the box, using the toolbar at the top of your page. Crop and style the image as needed to make it look sharp. Reduce backgrounds if they're not relevant to the image that you've just chosen.
Save each step as you go along--not every computer has an AutoSave function that will allow you to recover the latest steps you've taken. For faster downloading, save your image as a PDF file, takes less time to print than a regular page layout.
Print out or photocopy a rough version of the proposed flyer, and let the band review it. Take whatever feedback you get to produce a topnotch product--you'll need those first efforts to convince other bands to use your services.
Revise as often as your potential client demands, until both sides are satisfied with the results. Proofread for unusual names, clubs or places--particularly on how they're spelled--until you're certain that they're accurate. Go the extra mile until you're sure that everyone is satisfied.
Patience is a crucial As an unknown, you won't command big fees--you're helping someone shorten their never-ending "to do" list. The faster that your work turns around, the more demand you'll reap for your services.