One method bands are using is to do covers on youtube. This works only if the covers sound really good and they know how to Name the title with the cover band name, song, and their band name. If the covers are popular, over time start adding their own songs.
If your video view counts are large it acts as proof your band has a following and relevant.
Another tip is release a CD using CDBABY. You can release a single or album for mp3 download. With each video provide the link to your album in the description box. This could generate independent sales. That's another big indicator that would help the group seal a major deal.
Set up profiles on social media sites and keep them active. Share your videos and personal updates. You could also release single that's exclusive to your mailing list. Use aweber or mailchimp to manage your email list. These services also provide you the means to create an email opt-in form so it's easy for people to join your list. The html for the form can go on your blog, facebook pages myspace, and any site that accept html.
You should also make use of press releases to the media and music related blogs.
Boyce Avenue is a band that's used this method and many others. Check them out and how they landed their deal for a direct area to research.
I wish you the best of luck.