Reread this & realized I don't think I answered this...
Don't expect to make a living off of creating RPG material. Instead, figure out how you can do it despite the fact you can't make a living at it.
If you do form a company, be very careful to size it to your potential market. This means doing a lot of market research. (Which is frustrating because you'll probably get a lot more hints than hard-data.)
If you can find a non-RPG cash cow to subsidize your RPG habit, do so.
Create system-less material. My groups have always converted stuff to whatever system we're currently playing & mostly on-the-fly. So, the system-specific stuff just got ignored anyway.
Develop a reputation for quality.
Be online & encourage anyone who works for you to participate in online communities.
Collect RPG stuff like crazy (especially off ebay or from second-hand stores) & look for good ideas that have been forgotten.
Look for ways to improve the at-the-table experience.