Yup, it almost sounds too easy, but the best way is to do what you get paid highly to do, and convert that to ETH.

If your pay is relatively low (e.g. minimum wage or lower) there might be good tricks you can do online.  Like coinbase promos. Or odd jobs and promos companies do. 

But you have to realize that technically savvy people from low-income countries also have access to these opportunities. A driven techie in India making $10 a day is competing with you.  He's willing to go after $2/hour opportunities -- are you?