Welcome newbie!
In this business you get to hit the floor running because most companies don't want to give you more instruction than their general 'training' and the instructions that come with your job. So useful skills to run your business include:
accountant, collection agency, secretary, scheduler, actor, negotiator, photographer, computer geek, writer and route dispatcher.
And yes the requirements for every company are the same yet different and for each client within the same company are the same yet different. And once you have down a particular client with a particular company, the client may change companies and/or the requirements may change. Keeps you on your toes