The first step would obviously be scoring a corporate job. While there are a few ways to go about this, there are three main ways of getting your foot in the office door.
1. Dispatch Teacher
As a contract worker, you can partner with established English schools to teach outgoing lessons on their behalf. While some of the bigger eikaiwa offer training to instructors who are interested in doing off-site lessons, and the pay is usually higher than the in-house lessons, some smaller conversation schools will hire freelance teachers and dispatch them to their clients as well.
In both cases, the upside is that the school handles all the administrative details and provides basic materials, as well as in-house facilities for making print-outs or copies. Larger schools can also help you string together a number of different businesses to fill out your schedule. The downside is that they may take a more-than-modest fee from the lucrative teaching contract you could have had as a direct hire. And if your company loses its contract with a business, you may lose that work through no fault of your own.
2. Direct Hire — Corporate Program
Many of Japan's major corporations have longstanding English programs run within the companies themselves. Being directly hired by one of these companies is not as common as dispatch teaching—which may, in fact, be supplying some of the teachers for these same systems—but it definitely has its advantages.
There are usually fewer posts on job sites directly from a company seeking teachers, so the competition will likely be fierce. But if you can land one of these sacred spots, you can earn a very nice wage and have some resources provided by the company. This may include access to computers and printers, a budget for buying teaching supplies, as well as pre-approved texts provided by the company. Of course, this way of being hired may come with more scrutiny from the company and the higher pay tends to equal higher expectations for results.
Also very important to mention is that the number of lessons you teach varies greatly. Many teachers have to work for a few different companies, as these positions are often only part time or contractual, and only for a few months a year. Careful planning is required to solely teach business English.
3. Direct Hire — Tailor-Made for You
Another way to get started teaching corporate lessons to professionals is through building a reputation and word-of-mouth. Perhaps one of your eikaiwa students wants to introduce you to the HR manager at their company, or maybe you currently have one-on-one lessons with the president of a company and they want you to bring your skills to their employees.
While this option will almost definitely net a better pay than working through a school, since you're the trailblazer, it also means you'll be wholly responsible for the curriculum and creating lesson material. Furthermore, the onus for proving student progress, and thereby proving your worth to the company, is on you. You'll likely have little to no administrative support, and as a system that was created on a whim, it could disappear just as quickly if that company president just decides they don't have time for English anymore. This option basically offers all the benefits and disadvantages of near-total freedom.