I don't know how it works where you live, but here there are usually local music lovers who do amateur event booking/promoting... look for bands similar to you online and around in "the real world," make friends, and see how they do their booking. The best way, all around, is to network with other bands.
Also, depending on what your laws are like there, you might be able to play in bars/clubs as long as you make the gig 18-and-over, with wristbands or some other such device to keep the young'uns from drinking. Call the clubs you want to play and try to talk to whoever books the live music there. They might be able to work something out with you.
Other than that, your idea of splitting the cost of a hall with some other bands is a time-tested tradition and a damn fine idea. Call around to different places and see what the cost is for each one, find out if you have to get insurance and/or security, and go from there.
This all seems obvious to me, so sorry if this isn't all that helpful, but hopefully it was.