ER billing is done through the hospital billing department, isn't it? Or maybe not? I don't know that you will get any clients in that area. The potential problem with the other two specialties you listed is that they are usually in larger group practices, with billing/coding departments to handle things. So what to do? I would focus on expanding your parameters, and look at newer solo practice/newer small group practices, who may need someone. Use whatever contacts you have made in the medical world to network with. Maybe someone is looking for a new billing option.Or, forgo the idea of starting your own company, and pick up remote billing work if you can, for another billing company. If you are specialized enough, it isn't hard. I wasn't even looking for remote work, and just because of my answers to questions on various billing forums, I suddenly found myself working three remote jobs in addition to my full time job. Less hassle/work than owning a billing company, for sure.Finally, there are numerous threads at this forum about how to get that first client. Use the search function above, and review older posts. There is a lot of info to be found there.
I used to work for a very large company that provided the billing service for the ER and hospitalists at HCA hospitals throughout the country. I also became a supervisor and worked with a lot of the doctors who were very unhappy with the large company, but it is hard once they are contracted in to get them to go with a small person like myself.