See, that's why I hate the term digital nomad...
Digital nomads are simply people who make their living online so they'd be free to travel.
I know some nomads with a home base that travel 1-2 weeks off of a month, and some, like me, without a home base that go to different locations for few months each time.
However, the way to start is by having an online income.
There are so many ways you could generate income online... One of them is by offering online services, ones that don't limit you to a specific location. I am working a lot with Fiverr, you could see the services I offer there and take some ideas : https://www.fiverr.com/mayameyaroyo
I also wrote an article about how to generate income with Fiverr last year that might be of use to you:http://queenja.com/5-ways-to-make-money ... ng-fiverr/
As for teaching- again, being a DN starts with online income, and that could be achieved in many ways... I do content marketing, affiliation and influencer marketing. I know a DN currently in Chiang Mai that makes an awesome living in building websites (web design) you could also try to follow him, he has awesome insights: http://www.justinlight.com/
The online world is ever changing, the only way you could make a living in a year from now is if you learn how to educate yourself.
See what others are doing and try it out for yourself.
I personally opened my business, and once it was stable (after 11 months) I started my travels.
Anyway, I am sorry if that's not the answer you wanted, but that's what I got.
One last tip, when you do end up starting- pick a location that 3 months of rent + flight would not accede your current rent- it helps to have an easy start. (I'd start with some place like Chiang Mai or Bucharest).
Hope you'll find your way !