You have to start with PPL instruction.
Once you have enough experience, you can teach the non-instrument part of the CPL, but you would need an IR, or IMC rating to instruct the full CPL course.
You get by. It's not amazing, and having a second job or a partner with a steady income helps. If you're able to negotiate something of a retainer then it makes the winter months more bearable, even if it means you don't earn quite as much in the summer. I think most deals average out to the same thing.