There's lots of resources! I just started my rescue support organization last year and we are 501C3 certified now =)
Start with one dog, get a veterinary partner who will give you discounted rates, start a Facebook page and start networking your dog! The best way like tiger mentioned is to with your family and friends first and try to get your dog adopted, as you grow you can start to partner with petco and other stores to do adoption events.
Good luck and we welcome you to the rescue community, we can use all the help we can get for a world of no more homeless pets =)