Choose the person who will serve as the band manager. Professional managers typically have experience in the industry and extensive business knowledge with a focus on marketing. If one of the band members will serve as the manager, he will take on the responsibilities to promote the group, but all members can participate as needed to distribute materials, post to websites, and of course perform.
Build the press kit. Find a photographer to do individual head shots of each band member and a collection of images of the group on and offstage. Use the images in your promo materials. Each band member will need to submit a biography and music credits/discography if any. If you're just starting out, list the instrument and training, plus any notable music awards and highlights. The kit will include other materials as well, such as tour and performance dates, backline needs, business cards and manager's contact information.
Make a band flyer template that can be changed for different performances, then print and share them through various music, band and community resources.
Post the press kit to your website or to band promo sites. Also create band pages for myspace, youtube, facebook and as many social sites as you want exposure on. You can focus on just a couple or assign someone to update each site regularly. Sometimes bands are busy with rehearsals, shows and recording so designating a non-member can be very helpful to oversee the social sites and keep fans informed.
Create a Demo CD and have at least one video made of the band so people can see and hear the group performing. Demo CDs will have a variety of music. If the music on the CD is all original, make sure that is noted in the press kit, listing tracks and composers, as well as musicians on each track.
Get your name out in your community through bulletin boards by volunteering the band for fundraising and other events. Find causes your band can truly support. This is good exposure and you can sell CDs, give out flyers or brochures and business cards.
Join forces with a booking agent to get local gigs. It doesn't matter where they are or how acclaimed a club or facility. You want exposure. The more people who hear and see you and enjoy the experience, the more likely they'll tell their friends.
Upload music to online sites like CD Baby, iTunes and so forth. There are many different music sites, so scout around and start sharing your music for free and for the site's typical track cost.
Give out free CDs through contests or solely for promo purposes. You can also do "door drawings" for ticketed audience members at gigs.