Essentially what are the legal requirements for starting the next Binance, Bittrex etc. When I say in the United States I mean US based customers (preferably registered in the US as well.)
The US Gov hates cryptocurrency. In fact if you read recent laws (last 5 years) you'll find the language is vague + it can be construed that if you're a US citizen + you hold cryptocurrency, you may be in violation of law.
Better to simply stick with fiat currency produced by every government in the world.
Treat income management as a currency exchange proposition.
Whatever language you speak, just target selling whatever you're selling into a country that reverse correlates the highest to your currency.
So if you live in New Zealand + US currency is strong against the Kiwi, then sell product into the US.
This way you always win big, because some currency in some country will always be your best investment.