[DonRotolo]

Military & industrial is serious business. They'll pay a fortune for a product, but it needs to be (literally) bulletproof, with 100% service and a reputation to back it up. A semi-amateur start up wont have much of a chance.

The hobbyist market is huge and carries a lot less liability, fine for one-man operations and small start-ups.

The general public (non-hobbyist) is a dangerous endeavor, one lawsuit and you're dead. Tread carefully, and think long and hard on this one.

As for general business stuff - accounting, funding, legal, supply chain, marketing, purchasing, branding, etc... Buy a book somewhere, most are just fine for the basics.

Funding is always the issue, identify a customer with cash before building anything, and sell your prototype to them. Use that to find the second customer, and go from there. Be realistic when identifying your potential market size. A niche of a niche of a niche is rarely a large market.

Good luck.