When trying to build multiple income streams, you need to be (as you said) strategic.

Each income stream should be assessed in terms of how many hours a week it takes and what income will those hours buy you.

Writing on Medium, for example, doesn't usually result in a high average hourly income. If you spend 10 hours a week writing and get $200 a month, your average pay is under $5 an hour. If you're in the US, that's less than minimum wage.

However, if your plan is to leverage Medium, you could get gigs writing for other sites that may pay you $200, $300, $500, or more per article. If you write an article in two hours, that's $100 or more an hour.

You could also collect your Medium writings into longer e-books and sell them, that may net you additional long-tail income.

Finally, perhaps the most important is to resist trying to build multiple income streams in parallel. The best way is to concentrate your efforts on one, and only when it's well established and takes little time, start building the next one.