It's been about 3 years since I started playing out as a solo acoustic performer playing my own songs. I've noticed an interesting phenomena, which probably applies to bands also (none of the bands I was in before I starting songwriting lasted long enough for me to notice this phenomena).
At your first gig, or rather your first few gigs, of course you have no fans yet, so you invite your friends, family members and co-workers. You have a good turnout, because of the curiosity factor-- the "I didn't know you played music!" factor. But then once their curiosity is satisfied, they stop coming to shows, unless they really like your music; that is, they have become fans. Your closest friends may continue to come to shows for awhile longer, just to support you, but eventually unless they also become fans, you'll see less and less of them.
This can be discouraging. At your first shows you've got 10 or 15 people, now a year later, even though you're a better songwriter, a better singer, a better performer overall, only one or two people are showing up.
So once you've passed Stage 1; that is, after you've exhausted the pool of friends, family members and co-workers, the question becomes: how to you get actual fans? People who come not to "support" you, but because they love seeing you perform and hearing your music.
Ah, if I only knew the answer to that problem. I'd be interested in hearing how other singer-songwriters and bands have made this transition.